It was written to be that way, and in order to fully interpret what is going on as a 3rd party observer with a pan view outside the story world, you need to factor in all the things that led to the narrative been developed that way.
When blizzard wrote the blood elves in the TFT storyline, they changed philosophically from the high elves they were pre-scourge, the high elves of Wc3 RoC and of WC2.
They made them embrace fel magic - a massive taboo amongst the "noble " high elves - something their origin story fleshed out - they were dead set against fel, it is anathema to the high elf way.
If you read their early lore they were a group that were very protective and fastidious about using their magic responsibly in a way we came to understand was to distinguish themselves as much as possible from the recklessness o the night elves they once were, a recklessness that brought the legion and corrupted noble hearts.
They were strict and restrictive about magic, generous and more open hearted by allowing humans in, and sharing with them, prioritising others.
The blood elf that was developed in WC3 TFT (the expansion pack of RoC) and that was present throughout wow classic, was a bad boy high elf, a group that no longer cared about good magic, responsible magic, morals or ethics… they’d rip the heart out of you if it meant survival or gaining more power which they viewed as a direct necessity of survival.
In-game writes them describing themselves as shrewd and cunning and sneering at their former high elven ideals.
This immediately creates a philosophical and ideological distinction that makes becoming a blood elf more than just about mourning or respecting the dead.
In TBC the nation’s leadership and direction is written to have abandoned those high elven ideals and decided to embrace more radical and reckless means, in fact this is the basis for the alliance coming round to check on them (if you remember the TBC pre-event storyline, the panels in blizzcon 2005/6), on the back of the night elves stark warning.
This is because the blood elves have started using fel, a huge no no to the night elves and the alliance - as observed when Kael’thas follows Illidan to outland, at this point remember anti-hero Illidan (not yet made a villain) is not trusted and hunted because of this, and now the blood elves are taking this up.
Blizzard creates a reason for the high elf, or those who remain high elves to despite the blood elf for actually using fel and sucking it up, and abandoning all the ideals… this is used as a major tool to cause friction between high elf and blood elf - or do you completely forget the Silver Covenant questlines in WotLk.
Clearly blizzard isn’t abandoning or removing high elves, but using them as a source of friction between the horde and alliance.
However what happens is that blizzard doesn’t take the blood elves further into that bad boy direction, so while they initially start off bad, sucking fel, sucking mana out of beings, not restricting themselves from using “any means necessary”, making them kinda badass, they suck the light out of a Naaru, all this is redeemed about them, they are pacified largely over TBC’s events, a big storyline with the Scryers, interaction with the Naaru in Shattrath that ultimately leads to the being sacrificing itself to re-ignite the Sunwell with a blood elven people redeemed back to a less evil less bad boy, more high elven group.
That recklessness is tempered out and pushed to the fringes of the blood elves we follow, and they generally return to being high elf like - not as morally upright as before, but much closer and tending towards that. off course the Silver Covenant high elves still greatly embarrassed and furious at their kin for betraying their morals and their identity in TFT- TBC continue to persecute them, this isn’t helped by Lor’thermar expelling all those who retain the high elven identity away.
What does this tell you? It tells you blood elf becomes far more than what it was originally stated to by Kael’thas when the nation mourns the scourge invasion in WC3 TFT, it becomes more than are state of mourning as those who identify as blood elves start doing things very different from what is high elven traditionally.
So blood elf is now an identity, more than just a change of name established in TFT through to TBC. Now the observation is that blizzard then developed the blood elves from TBCs story onwards back into essentially high elven in character even though there now exists an identity difference in the in-game narrative between blood elf and high elf. But overall in general, blood elves are modelled back into being high elves with the new identity that becomes less and less distinct from the high elves like it was in the TFT to TBC stage.
So that effectively you feel you are essentially playing a high elf on the horde. Because blizzard wanted people who like high elves and that side of the alliance to switch to the horde to populate it further and even out the numbers.
The direction is intentional, they wanted the blood elves more high elven, so developed them so because they wanted an alliance race on the horde behaving very alliance minded, so they tempered the blood elves.
And so while technically blood elves and high elves are ideologically different, this has been whittled down to being essentially only different by being loyal to a different faction because the blood elf character is so high elven at this point mostly, and the animosity is really based on the blood elf populace behaviour and actions during the TFT to TBC era rather than anything after.
No, blizzard after TFT, well after, in chronicles mainly , but in the post TBC era is where they then go back into the lore and show that the high elves were not that close to humans before the TFT events.
This is what I am referring to, I’m not referring to when Kael’thas is persecuted by Garithos and seeks help from Illidan via lady Vashj and joins his group, this is when the blood elves start moving away from the alliance they are part of at this point in the story.
When this was released, many of us assumed that elves and humans had been great friends since the elves and humans fought together to beat the trolls when the nation of Arathor was young - a collaboration that led to Dalaran being founded and built, the Order of Tirisfal and a lot lore that seemed to have humans and elves friendly.
This lore was later fleshed out post TBC when blood elves are made horde, to show that pre WC1-3 time period the high elves were a lot more distant than it had initially appeared. They flesh out WC2 after TBC to make Anasterian and the high elves reluctant to have anything to do with the humans and alliance, and that actually only some high elves seemed interested.
This is generated to put further distance between the high elves and the humans so that players can accept the blood elves as less tethered to the alliance. It is added lore help make the blood elves feel less belonging to the alliance… I believe it was done to put an end to threads like this.
however it is in the very make up of the story… the alliance is themed upon all the things the high elves and humans are about… their view of society, life, nobility, law and order, complex religion, approach to life, study, knowledge, arcane magic, cities and civilization in the type of format that the high elves and humans and dwarves have - these are all the things the alliance has that primarily defines it. Furthermore the elves and humans have been collaborating for 3,000 years before the events of WC1, and it is too ingrained in the lore for them to remove. furthermore, Wc2 is written with the Orcs and Trolls trying to burn down Quel’thalas, and WC3’s scourge attack has the undead destroying them, the undead that are a horde race in wow.
When wow was released, it is clear the blood elves were not written or created to join the horde. It is clear to anyone who followed the franchise, that the Night elves and Forsaken were designed to be their own factions. It is a gameplay decision later on in wow’s development to make it only 2 factions, that caused te Night elves and the Undead to be broken down to fit in the 2 faction format.
when decisions like this happen, the game creators change the lore, they write new narratives. When the alliance overwhelming popularity was problematic tot he game systems that needed an even distribution, this is when they came up with the plan to use an alliance race, an attractive one to go to the horde to lure players on. it is at this point the blood elves are now envisioned to the horde, and new narrative material written to make it happen.
It is clear this was not the original intention, the high elves were not designed to be a horde race because they end up being horde members in TBC which many of you who never involved with the franchise before that era might think. You are probably use tot he blood elves always being horde, but if you look closely it is very easy to see that they are an alliance themed race, with far more in common and alike with the alliance
In fact they basically do the alliance themes better and in a nicer way than the alliance, and his is part of the reason why the alliance is not popular and feels lame, the horde does the alliance better than the alliance.
It is also why the alliance keeps asking for high elves, but never asks for Orcs, Trolls, Forsaken, Goblins, Tauren etc, it is because the high elves are traditionally alliance, and the blood elves are themed entirely on that, not on any horde race.
They don’t desire any other horde races, only the ones that are alliance based. The blood elves, and the Nightborne who are the night elven subrace.
I believe my essay above has actually addressed all the points you have made after that point .