I think WoW Classic has some good ideas, or perhaps I should say Moder ditched those ideas to make the game casual friendly.

I posted several stuff I think Classic does better like more unique class balance, more cohesive world true to Warcraft (or fantasy) ethos or just having the world feel real and populated because people are not flying around on their personal shards.

It's not to say Modern doesn't do the right things too. There are 15 years of quality of life stuff baked in after all. The end game of Classic was also pretty dry with only 2 dungeons and 1 raid to run and no PvE solo content at all.

Still, those will still last for a bit and who knows where people will go from there?