I doubt they think -that- far ahead, I mean that was at least a decade ago, and a completely different writing team, We’d already seen both Blood Elves and Eredar (so basically Draenei) before WoW was even released, back in the old RTS games
That’s possible, but more likely is simply that when they decided Blood Elves would go Horde, they had to make Quel’thalas explorable (Which it wasn’t in Classic, but was in the RTS) and add Azuremyst and Bloodmyst isles. Because that makes sense. Two islands that close to their shore and the Night Elves never thought of going “Shall we colonise them? No one else lives there…”
Sure they do, Their lore starts in WCIII, which is when they rename themselves as Blood Elves
You’re right that they are rebranded High Elves, I mean that is literally what they are. High Elves who renamed themselves Blood Elves to honour the fallen after the Scourge invasion. Their relationship with the Horde is more a response to Alliance aggression. They are smart enough to realise that Thrall’s Horde was different from the Orcs that attacked Quel’thalas during the Second War, and smart enough to realise the differences between Amani and Darkspear (I mean they -physically- look different) The Tauren were not involved in that because the Horde hadn’t even met them yet, and the Forsaken didn’t even exist in the Second War. So of the Horde races, the only one they were ever at war with was the Orcs, and as I say, Thrall’s Orcs were very different to the ones who rampaged through Quel’thalas.
On the other Hand, when it comes to the Alliance (With whom they were neutral) The Humans did the dirty on them in the form of Garithos and his army, I love how people try to say “But he was one racist” “Really, is racism a superpower? Does it allow one man to arrest an entire army and it’s Archmage leader?” Nah, that was Garithos’s army as well as him, so yeah, Humans did over the Blood Elves. Then We have the Human kingdom of Dalaran, who were perfectly cool with the impending executions, again, humans, Then we have a Dwarven spy collating information, taken from the body of a Night Elf saboteur, who was just one member of a Night Elf incursion of quite some size, backed up by naval assets. So really, the Alliance kind of drove the Blood Elves into the Horde, the same as they would later do to the Nightborne and the Vulpera. They really need to work on their diplomancy!
You pretty much described all of Wow’s elves, and you’re right, Warcraft Elves are smirky, and arrogant as all hells.