Jumping back to Vanilla one thing I hate about the current expansions is quest helper and honestly this rings true for other games (Destiny for example) as well. I think the lack of a quest/mission guide is a better experience for the player. I remember playing BC and had a blast trying to complete quest. You had to really pay attention and read the quest for specifics and clues to figure out what was needed or where to go. The completion of quest back then felt so rewarding. Now you just look at your map and follow the "little dotted line"[1] then rinse and repeat. This struggling with quest is what I'm most looking forward to with classic WoW.
Edit: words
That crowd in the city, coupled with the worse trace options- back when mounts were for higher level players and were very expensive - made the actual quests feel a lot more remote.
Special mention to the griffins/hippogirffs. One of the greatest moments of joy I felt when I got on one the first time and could still look around as it flew.
I remember that experience of discovery. It only lasted as long as it was all ... undiscovered. I don’t think it’ll work for a repeat performance.
Look at EQ. The base game is freemium, but if you want to play on the latest progression servers, you need to pay their subscription price.
And another minority who wants the equivalent of EQ's progression servers - they don't want to be stuck at 1.12, they want all the same content releases again.
And another minority who wants TBC. Another WotLK.
Blizzard is going to be disappointing someone with every choice when it comes to classic. And a lot more people are going to be disappointed when they actually go and play that game.
TBF, you couldn't pay me enough to go back and play a warlock with all the prep required to raid Molten Core (and all the "limited debuff slots" BS). That's a lie of course, I'd happily even mule a Paladin for your guild if you wish to pay me $300k+ a year.