Vanilla wow had some things that were better than modern wow(well last time I played). Most of it was absolute fucking bullshit and anyone with an ounce of memory remembers, it's like how when people talk about good ole EQ times.
Consumables situation, 40man raiding, molten core, 50g respecs, servers crashing and burning for pretty much all of vanilla until BC besides a few servers, faction massive imbalances in pve and pvp(windfury pvp, blessing of salvation in pve), alterac fucking nonsense, terrible terrible class tree design(LACERATE SUP), molten core, tranq shot rotation fights, downranking heals, chinese farmers EVERYWHERE, flying for 10mins to go to Silithus, tier 1 and 2 stats until they were entirely redone, molten core, onyxia cloaks, taunt resists, fear based raid bosses, fury warriors threat control aka "k I'm pulling aggro to reset threat, someone rez me please", raid wide curses that have to be removed 1by1 with shitty UIs then nerfing the mod that made it easy, world bosses actually mattering for progression(green dragons) and molten core. Probably forgot a bunch of bullshit, but that's just what I remembered in 3mins of thinking of the good ole times.
On the plus side, world PvP(BRM camping, killing farmers in tyr's, AQ gates opening wars on silithus), more competitive BGs due to not being cross server(sadly double edged due to shitty queues and people dodging), fun and new leveling experience in a mmo, continuation of the WC3 story, AQ(20 and 40) and Naxx, etc.
There were some good things, but fuck there was a lot of terrible shit I wouldn't want to play ever again.