WoW's pivoting away from the things people liked in classic was by design. Most of the good things of WoW classic were coincidental and largely taken from EQ.
EQ was always about the journey and the community. It wasn't a race to max level to go sit in a queue to get gear to sit in another queue to get gear ad infinitum.
Why do you think they relented on having a classic server for so long? The designers legitimately don't like the part of classic that actually appeals to people.
Actually, a lot of it has to do with the fact that most of the Blizzard development staff left sometime before launch, iirc. It's unclear whether they left of their own accord or because of "restructuring" but a lot of Blizzard devs left to Arenanet to make Guild Wars 1 (and left before GW2 was made, which tried to be a fucking WoW clone) or the Hellgate: London team.
So shortly before release, Blizzard ceased to be Blizzard, and the main people left in charge were the likes of Furor, Tigole, and Enoyis who were "hardcore" guild leaders in Everquest. They wasted no time shitting up the game for their idealized raiding endgame, making excessive grind a part of damn near everything, and shitting up classes. The biggest reason why Dire Maul was a better dungeon than most shit that they came up with later is because it was already designed for the most part by old Blizz back when the WoW team wasn't just absolute raid-whores and they just slapped finishing touches on it for release.