A lot of what I get from this is that there’s a certain level of narrative dissonance within the game itself.
There are things the game says are important or meaningful narrative things, but at the same time, if you even briefly analyze the overall story, it doesn’t have any kind of logical consistency. I think it’s also a matter of “well, that’s how they were first depicted” and, honestly, first impressions are tough to break - especially when the game’s story can flip flop on it too.
Things like fearing or being wary of Death Knights, Demon Hunters, or Warlocks is partly because that was how Blizz modeled you should react to them. And yeah, at times they decide to shift gears and say, “Ah yea, they’re just sorta accepted now,” but then pull a 180 back in the other direction.
DKs are a good example: presented as monsters in Wrath, then sometimes show up as just regular Alliance commanders or soldiers, but then in Legion they’re slaughtering Red Dragons and attacking Light’s Hope Chapel, and now in Shadowlands seemingly almost good guys again. So… is it right to keep them at arm’s length or shake the hand of the next DK keeping a portal to Shadowlands open for you? Well, who knows, depends on what narrative point Blizz needs you to accept at that time.
The Warchief thing is partly because a major selling point of the Horde as a faction theme was the idea of a Warchief. It’s part of why Alliance made rabble over the High King concept as a “Blue Warchief” - it felt like a lame version of the Horde’s themes, rather than reinforcing the Alliance’s. I’ll be honest, the idea of a Warchief is just kinda cool - and as a game that distinctly relies on the Rule of Cool as a narrative tool, the idea of folks still being a-okay with a Warchief, IC or OOC, makes perfect sense.
And sometimes you’re just drawn to one particular storybeat and have a Strong Opinion about it. For example, I prefer TBC blood elves immensely more than what’s come after. For me, giving a Naaru the succ and spitting in the face of the Light is forever cool just as such a unique theme of Paladins. So I would most certainly play a Blood Knight much, much closer to the TBC era mindset than the modern one. Is that necessarily wrong? I don’t think so, it’s not like cultures are monolithic. Would that make me a bad roleplayer? Probably to some folks. Granted, this is all just an example of a niche situation, but for some races like orcs, old tropes die hard.
Anyway, long and short of it is that because people have different embedded concepts of what makes a “thing” that thing. You’re also sometimes counter-acting older tropes, strong first impressions, and so on that can be really hard to pull the community away from even if its not consistent with current lore. Doubly so if Blizz tends to waffle a lot in the presentation.