I think the races that compose each of the playable factions are an integral part of their identity. The Horde has mostly been considered as the savage, evil, tribal and monstrous faction while the Alliance has mostly been considered as the civilized, good, advanced and patronizing faction. This, of course, has changed in recent times with the addition of hope-preaching orcs (saurfang) and insecure trolls (Zekhan). This may be seen as an attempt to display diversity among the two factions but i, personally, see that as an attempt to whitewash the races' defining characteristics (Warmongering orcs, malicious undead, greedy goblins and so on...). For this reason, i believe the Ogres and the Forest Trolls are a crucial part of the Horde's identity while the Wildhammer dwarves and High elves are a crucial part of the Alliance's identity. The Ogres have been a part of the Old Horde, Horde of Draenor, Dark Horde, New Horde, Fel Horde and Iron Horde, while the Forest Trolls have been a part of the Old Horde, Horde of Draenor, Dark Horde and New Horde. Meanwhile, the Wildhammer Dwarves have been a part of the Alliance of Lordaeron, the Alliance Resistance and the Grand Alliance while the High elves have been a part of the Alliance of Lordaeron and the Grand Alliance. Thankfully, in the Shadowlands expansion we are getting to play as High elves and Wildhammer Dwarves as customization options. But, alas, we will still be unable to play as Ogres or Forest Trolls on the Horde side.
This leads me to my next point, the exchange of some of the races between the two factions. As i said, the Horde has mostly been an evil and savage faction while the Alliance has mostly been a civilized and good faction. Even though lore doesn't support it, i feel like the Dark Iron Dwarves, the Worgen and the Void elves aesthetically fit the Horde more while the Blood elves, Nightborne and Vulpera fit the Alliance more. The Dark Iron dwarves have always been an evil race, a dark counterpart of the bronzebeard dwarves. The worgen have always been a savage and brutal race. and the Void elves (basically the Warhammer Dark elves) are like the dark counterpart of the Blood elves (Although they don't seem to be evil, they should definitely be, as they deal with the forces of the void. Plus, them being banished from the alliance for delving in the void and being embraced by the horde makes much more sense than the other way around). Meanwhile, i feel like the Blood elves and Nightborne are way too civilized to be associating themselves with the barbaric Horde (plus, there are already High elves and Highborne on the Alliance, so it makes sense for them to be a part of it). This will also solve the whole issue with High elves being on both the Horde and the Alliance (by just giving them to Blood elves) and the problem of their racials (as the blood elves' arcane racials fit them more than void racials). And as for the Vulpera, i feel like they are way too sweet-talkers to be part of the Barbaric Horde.
What do you guys think?
Do you agree of disagree? share your thoughts.