I agree with you often, but here we disagree. Overall the Horde has been more beneficial, and more trustworthy for the Blood elves than the Alliance has proved themselves to be. It is completely realistic to see a hatred of the Alliance that grows even with the past crimes of the Horde against them, the Alliance is more current in it's faults against them, and it's compacted by the fact that they used to be allies, making the numerous perceived betrayals even worse. Liadrin states something similar that being part of the Horde was not always easy, but it allowed them to carve a place for themselves where others mistrusted them or fought against them. Even a light devoted paladin like herself perceives the Alliance as an enemy.
As an afterthought, doesn't it seem a bit strange to cite racial distrust as being a somewhat universal and intrinsic to the day-to-day life of a Blood Elf when there was at least three groups who became disenfranchised with the Blood Elves and who re-joined the Alliance, yet haven't once spoken of or even hinted at racial mistrust? Umbric is a pretty good example of someone who, in all likelihood, was present with Rommath when they were arrested in Dalaran -- yet he didn't even give a second thought to joining the Alliance (and, like Alleria, they both still explicitly state they fight for Quel'thalas) nor did he balk about working alongside humans despite having been a part of the group that apparently hates them with a Rwandan-esque fervor.
I'd say Umbric is a special case where he was prostrating himself before Alleria as his savior, she saved him from insanity, and therefore he and the velves would follow her because she saved them. As I said before the elves already in the Alliance or joined the Alliance, were social outcasts anyways, even before the official split. (Vereesa the big example)
Every nation is a hypocrite in that regard, it does not change however, that the Alliance did not actually come with an offer of allegiance or renewed friendship, they shot themselves in the foot by making the walking dead a more viable, and friendly choice of ally.This would fall into the category of "contrived explanations". It's a game set in a sort of medieval, fantasy setting -- you may as well expect anybody with a pulse is going to be spying for someone. You think the Blood Elves didn't have information flowing to them from the various frontages? Be real. At best, this is just shoddy reasoning for Blizzard to affect gameplay by giving the Horde things that would bolster their population, at worst it illustrates that the political class in Quel'thalas is either inept or hypocritical.
I already adressed this earlier, but I'll tldr it. They are the exception, not the rule, the high elves with their human fetish, and the void elves with their loyalty due to Alleria saving them(the velves are met with prejudice in parts of Stormwind too, last I checked, I didn't roll one my self to check.)And yet not one, or even two, but three distinct circumstances have arisen wherein large ("large", air quotes being necessary) clusters of individuals completely defect to the Alliance and aren't subjected to immediate racism or prejudice.
Except that's not a proper example. They aren't joining Mexico, they are joining the rebels who ran out the guy who butchered parts of the Us. They didn't want to ally with them at first, but in with Canada in this real world scenario first trying to execute the President/leader of the Us, and then spying on the efforts to rebuild under the pretense of an abassador outreach that had no real plans to actually help, kickstarts that unlikely bond, a bond that grows when later down the line Canada (What an odd real life comparison) pulls a similar stunt and kills more of your citizens.It's because it doesn't jive with how the real world works, which means as a viewer/reader, you cannot suspend disbelief when obnoxious decisions are made. If Mexico sends a million soldiers to butcher their way through the southwestern U.S., whereas Canada arrests a bunch of reservists we sent to help them (who then broke Canadian law), it wouldn't be logical to then join Mexico against Canada -- the punishment doens't fit the crime, so to speak.