I understand the idea behind allied races, if you like the model of the blood elf but in alliance - use void elf, if you like night elves - use nightborne elves… but whats the point in races like lightforged draenei and highmountain tauren? They are in the same group as their original model and it doesnt make sense to me. Dont get me wrong, I love these races but they should have been just an addition to the barber shop. OR they should be in different factions… Like, dark iron dwarf were bad guys, why should they pick alliance? Or kul tiran humans - alliance abandoned them. (Ok kul tirans have a good reason not to join the horde but you get my point). Give Alliance the trolls, and give horde gnomes (please dont give us gnomes this is just a figure of speech, thank you)
PLEASE DO GIVE US GNOMES!
But I do think bad guys can be Alliance aswell… A faction is based on idea’s and principles, not if your good or bad…
Horde is full of good guys and Alliance is full of bad guys aswell…
Alot of the bad things that happened in the Warcraft universe is caused by the alliance, from Medihv, to Arthas, to Sylvanas (now a good guy), to Ilidan, The enslavement of Thrall,… All caused by… THE ALLIANCE.
Obviously Grommash was no softy either
And ofcourse Horde had Gul’dan (corrupt, but empowered by Medihv, yes an alliance…), and the Fel Orcs who were tricked into drinking demon blood… but that doesn’t represent the Orcs, or the Horde itself…
A quick quote from the fandom website I agree with:
The Alliance think of the Horde as brutal barbarians who would ravage and destroy their lands due to the acts of corrupt Orcs and Undead - (in the original Warcraft mythos Orcs and Humans were bitter enemies and despite new leadership they still distrust one another due to prejudice and injustice on both sides). In return, the Horde think the Alliance are arrogant tyrants who consider themselves superior to them whilst viewing the Horde races as sub creatures. As such the Horde worry that the Alliance would hunt them down and destroy them.
TLDR.
Both factions have good and evil characters
Both factions view eachother as evil - bad guys.
Clearly Alliance is pictured as a more “monarchy” faction , Horde as more “Tribe-like communities”
Not all of us were. The Dark Irons were split between the Ragnaros-loyal group, those loyal to Moira (Alliance), and those in the Thorium Brotherhood (neutral).
I like the variation that Allied races bring to the game and also the addition of new areas.
Eg. Boralus - Kul Tirans
Unfortunately, not all allied races got a reasonably sized, interesting cultural area, which is a missed opportunity imo. Dark irons, void elves etc.
I wouldn’t mind seeing a lot more factions develop as an alternative to just the big two.
Neutral (PVE mode) could allow all races freedom to move and trade within the public areas of any faction, while being carefully watched by any guards (Maybe even followed by a stealthed npc rogue in some cases).
It would be interesting if character choices (quests accepted, political / moral stances etc) developed deeper ties, more varied opportunites, and unlocked specific areas, access to higher ranking npcs etc.
This might become too much of a crossover with reputation idk. 
imho the only “nonsense” allied are the LFDraenei. Invented back in legion and left there…
Even the velves are just a creation to appease helves alliance fans.
Personally i love the allies and im getting to 50 with every (except maghar- wip) but probably blizz should put more love on them (and i think about NB feet)
The RP that has been played out so far with Calia Menethil and the forsaken could be a stage for the forsaken to become an independent third faction in the future.
Probably without restrictions on what race can join.
Oh you mean like when Blood Elves joined the faction with orcs, troll and loraderonian undad after orcs raided their cities, troll had been in war with them since forever, undead destroyed their capital and lordaeroians used them as meat shields.
Also why didn’t the Nightfallen join the Alliance, I mean the Horde send out the Blood Elves (or more specifically the Blood nights) while Alliance send the Night Elves and the Silver covenant to aid in the retaking of Suramar. It’s all petty reasons really and you can apply that to almost every single race that has joined either faction. Blizzard have made their job really hard in justifying why someone joins X faction because it’s only a binary choice and a lot of the races have more nuances to them. NEs for example, well you don’t like either faction but the green boyz chopped of some trees so I guess your blue now.
People also pick their race for the fantasy, not just how they look. It’s certainly true though WoW lacks the depth to really give that much meat.
There is not enough depth for allied races to be justified. That being said here is my opinion on every single one of them.
On the Alliance side we have:
Void Elves are Blood Elves who decided to study something forbidden.
Dark Iron Dwarfs are just evil Dwarfs
Lightforged Draenei are regular Draenei who decided to fight some demons
Kul Tirann are only allied race on the Alliance side that have some sort of the story and meaning thanks to Jainna and her history.
Mechagnomes are just regular gnomes with mechanical limbs
And on the Horde side we have:
Nightborne Elves, sofisticated Night Elves who sealed themself from the world
Tauren with antlers because some ancient dude saved a deer
Mag’Har Orcs, Orcs without fell and corruption
Zandalari Trolls who like Kul Tirans actually make sense and are a good example of how to make allied race. Rich history and perfect sense story wise.
Vulpera, on the 1st look they are unique but soon enough you realise that they are just hairy goblins with tails.
The point is that all allied races share the most of the history with our regular races and with that their fantasy is the same. And only thing that would matter is do you want to play as an Alliance or the Horde because you have the same races in every faction but with a minimal change to justify their racial spells.
Even then when ye get down to it Kul Tirans are fat humans. Lotsa personality, I like the Tirans, but the allied races should be customizations. And they aren’t 'cus the grind to unlock them (extending subscription payment model) + faction changes = money for blizzard.
If there were to be any argument for making separate races, it might have made sense to swap Dark Iron Dwarves for Zandalari Trolls / Highmountain Taurens. I mean the alliance got blood elves, what did the Horde get, Nightborne? Barf I guess they got Vulpera which, fair play, is fairly new.
Lightforged Draenei, Maghar Orcs, Highmountain Tauren, (maybe also Dark Iron Dwarves) - these all make the least sense as distinct races to me, especially on the same faction as the races they derive from.
And the Mechagnomes… I think concept might have been good but the execution was Heaving Barf. Definitely should have been a customization option for Gnomes to have mechanical limbs, though why you’d want to escapes me.
Too many things depend on the bifaction system to seriously think of a playable third one. It would be easier to create another game than doing that. What could happen with the Forsaken – and I doubt it because of how the new undead elves customizations were added – is something similar to the Pandarens, which would mean being able to join both the Horde and Alliance following different leaders.
That’s exactly what I mean!!! 
I personally like the Allied races, aside from Lightforged Draenei basically making Draenei more light based and on the same faction too. Makes no sense and a bit boring.
The best of the Alliance allied races would be Dark Iron. A classic old race, with cool different aspects to modern dwarves. The Wildhammers were just added as customizations because they look similar.
Void elves were just added as a way to give Alliance high elves with blue/purple gothy dye everywhere. By doing so they ruined a perfectly amazing character we had since Warcraft 2 (Alleria) and made her into sylvanas gothy version 2.0.
Instead of giving the Alliance a race they had as NPC’s since Vanilla, but simply giving them unique hairstyles, racial, and tattoos. They went with something new and unexpected. Don’t get me wrong I love Void elves, but their introduction was rushed and out of the ordinary and their place in the alliance makes little sense as to why the alliance accepts the void more than the Horde does. They are even bullied in Stormwind especially the Cathedral district. Can’t even imagine their relationship with the Lightforged, or Alleria’s relatinship with her husband who if they try to make another baby might end up nuking Stormwind by mistake.
Oh and with the introduction of Undead (AKA gothy elves 2.0) the void elves are basically less unique now.
I love the Story of the Highmountain personally, even though there is little distinction between them and the Mulgore taurens. One thing I hated is how each tribe didn’t have their own special tattoo colors, would’ve made them amazing. Instead majority of the Highmountain, no matter what tribe they come from wear red. This is how I would’ve done it
Blue: (Rivermane)
Red: (Bloodtotem)
Green: (skyhorn)
White: (Highmountain)
This would’ve been amazing in my view and helps with Roleplay better.
The Mag’har orcs are really great because you have different tribes to play with and if you play WOD you can get some nice gear too for each tribe.
The Zandalari are also great and have some nice story to them.
The Vulpera while have a complicated experience with some, are actually a great addition. They are resourceful, surviving the harsh climate of the desert for years, great travelers. They are basically Goblins but even cooler. I think people need to stop making assumptions that because you play an animal race you are a furry. It’s a old joke that became a stereotype. I know a friend who played Vulpera simply because he liked the lore and the desert aspect of them. Plus Foxes are his favorite animal.
Nightborne are actually cool especially with the recent customization options. They became more like their NPC’s. Even if they do resemble Night elves a bit, they are at least on a different faction. So it’s fine.
Kul Tirans I feel like I have mixed opinions on them. They are just bigger humans who have a love for the sea, problem is, Kul’tirans are not all big and even their leaders are not the same size which makes it very confusing. You also have the extremely skinny ones too.
Mecha Gnomes. Not really a big fan of them at first, but then someone with a disability explained how he liked them because he had a mechanical leg or arm (can’t remember which) and yeah that’s why he likes them.
You can have the Leper Gnomes.
We already have gnomes. In 90% of my cooking recipes are gnomes included.
Everyone liked this.
But we already have Goblins… If they aren’t Leper gnomes then I don’t know what they are…
They’re not real. You’ve been imagining them all along.
This. This. This.
They implemented it in such a weird way. LFDraenei should just be unlockable customisations like the dark ranger skins in the most recent patch. Same for Mechagnomes, they should just technically become a mechagnome once the “upgrades” customisation option is selected on a gnome character in the barbershop.
when they talk in the past about allied race for gnomes i considered mandatory the presence of lepeer gnomes from gnomeregan. I was so disappointed about the mechs…