As someone who really no life fit and played WoW, Dwarf Fortress, and EVE in my 20s, you didn’t miss much. My most momentous EVE achievement was betraying my online “friends” who had mostly stopped playing, blowing up all their expensive ships for the insurance payout, then like a true space pirate losing all my ill gotten gains playing Space Poker.
EVE (and other MMOs) had their moment and the ideas of MMOs with a persistent lived in world were very cool but the moment for them seems to have sadly passed beyond the horizon for whatever reason. If you had asked me 20 years ago I would have told you MMOs were the future of gaming.
It's worth saying that whatever they call it, GTA: Online is basically an MMO and it's one of the top three most popular game on Earth iirc. In fact I think only Tetris and Minecraft beat it.
Looking at what GTA6 is shaping up to be, and wondering how R* is evolving the online side, I think we might simply have seen MMO's turn into something people our age don't recognize.
I still can't figure out what the appeal of WoW was, but I'm guessing it was the insanely large community?