I like how your trying to get a good solution to the problem, and there is a problem with “minority faction” i am part of a minority faction on my server so i can empathise.
I think if you look as to why the alliance are “low” on numbers is this, at 60 all real minmax went ally as it was the better faction, while still there were a lot of horde, reason there are a lot of horde is they move from retail with friends, or they came back to play the faction they always were and as we know on retail the imbalance is heavy horde this translates to here. Now the minmax group that were alliance all went horde and this is that 10% population loss or so.
Any reward you give for alliance that i can think of will negatively impact the game, box’s with items (even if soulbound and i do think they should be soulbound) will change the value of items, giving more honour/marks will only make people “done” with pvp sooner and then lower the need for these things, BoJ means less need to do pve (already lower on a minority faction).
Imo in order to “fix” the faction imbalance (that is according to ironforge 45.9% ally 54.1% horde world and 46.1% ally 53.9% horde EU BUT 39.3% ally and 60.7% horde for EU PVP realms) i think we need to look at the underlying core problem, alliance in general do not enjoy pvping, if you look at the general EU numbers, then look at the “old” que times for horde, 1h 30 min for a wsg, on avrage a game is about 20 min, with a near 10% population difference, but a que time of 1h 30 min longer, this to me looks like you have 4.5 horde players que to a bg for every 1 ally player. This number is far far different from the population numbers. And according to ironforge 66.9% of ally on pve servers, and 33.1% horde on eu pve servers.
So i have to ask why do ally in general not like pvp? obviously getting ganked in open world when you are already a minority faction is a factor, but i do not think the root cause of this. Horde que times were up to 30 min at lvl 60 also.
In all faction v faction mmorpg, the minority faction on a server once beaten cant recover, you cant world boss’s you cant get groups because you die going to dungeons, you cant farm because you get killed due to imbalance. Its a system that is set up to fail.
So a “drastic” idea but what if you had a pve layer on pvp servers, where there was no world boss’s so it cant be cheesed? do you have summon stones a “safe zone” where pvp cant take place, so minority factions can still pve?
In short i sympathise with the difference on pvp servers, and i dont think “just go pve” is the right way to look at it, im very grateful for the HvH BG’s as it means i can finally pvp, but i would like to try and help the alliance with there problem, i do not think a loot box will change anything other than damage an economy, we need to look at all reasons why ally doesnt like to pvp.
As for removing premades, i do think there is a better solution, if you allow people to que as a raid, but have a timer cap on facing a pug of 10 min, so if another raid team cant be found in 10 min you can face a pug, this removed the vast H/H gain from premade but allows people who like organized bg v organized bg to keep playing, it allows people to play with there friends, and means pugs will normally face pugs, and pre will normally face pre.