To be honest, this equivalency does not really hold up too well.
The Draenei are, per definition, those who rejected the ways of the Eredar and are victims of the same group. They were the same race originally, yes, but they are distinctly different people. If a human meets a random Draenei, he is guaranteed that said Draenei is not an the same person who, as an Eredar, caused his people harm/grief.
The orcs are much trickier. The vast majority of Orcs drank the blood and became corrupted, only to later lose that corruption. They are the same people, just in a different state of mind. If a human meets a random Orc, she is very likely that said Orc is the same person who has caused her people harm/grief.
That is at the core of the issue, especially with those other examples. Most of the time, those who are corrupted stay corrupted and thus hatable, but they don't represent the majority of a race. Arthas does not represent all humans, Sylvannas not all high elves/undead. That makes it easy to not extrapolate from them to the whole race, since our brains allow us to recognize them as exceptional individuals more easily. The Draenei come closest, but they have the advantage of being of a different phenotype, and the alliance specifically knowing that those are the ones who refused.
However, the orcs make it really hard for the human (as in our human brain, presumably shared by most sentient races on Azeroth) to make that distinction. In the majority of cases, a given, specific orc was part of the invasion, was part of the horde that came, murdered, pillaged. Knowing somewhere that they at least claim to have only done so because they were corrupted, is much harder to process. Which isn't even getting into the at least somewhat reasonable distrust that people would have in that explanation in the first place. Remember, these are characters in the story. They aren't like us, who have the word of god that the orcs only did what they did because of corruption. To them, it is just what the Orcs claim, despite still being inherently focused on war and not exactly reluctant to go kill others when their warchief commands. The past few years, in universe, have not done much to quell that doubt.
And even if it could be quelled, a person's brain is not well-wired to truly understand such a concept. Just imagine for yourself that some army unit from a country came into your town and started killing civilians, people you know, maybe you even care about. After they are is caught and imprisoned, they are released since they were mind controlled or something and released back into society. Would you, when looking at a soldier from that unit, be able to disregard the image of the murderer from that of the man in front of you? If you can, congratulations, you would be in a very small minority. Most people can't.
That is pretty much what happened in WoW, in a way. There are some who can fully internalize the effects of corruption on others and act accordingly. There are many more who just can't. And heck, you can even find alliance members who distrust Draenei for looking like Eredar, Night Elves for what happened in the past, etc. It's a very personal thing, but it is much easier when the issue can be focused on one singular person who caused it, harder when the majority of a race is still the same people who hurt yours. Treating all these cases the same is just....overly reductive, in my opinion.