I don't want to let my glasses get too rose-tinted about EQ; a lot of what happened in the game is what people now would call bad design and inconsistent, buggy performance. Back then it was revolutionary though (along with DAoC, UO, ect...) and players worked around, with or through the quirks to arrive at ways to deal with content that the devs never foresaw.
And then Verant did something very few companies today do: they let the weirdness and somewhat buggy things stay. So there was a real sense of "yeah, we kind of created the game as it's played today" from EQ players, because we were responsible for devising the mechanics that all players operated by. Feign Death pulling as an example. Or like, learning how to pull without aggroing things through the walls and floors was an art form, not because Verant planned it that way, but because their code was pretty rocky. But in being rocky and quirky and somewhat buggy....players took it upon themselves to make it work by understanding the game and it was taken as a challenge, not as "fuck this buggy, imperfect system."
And then WoW rolled in and provided people with this highly structured but very polished and consistent game play model....and people traded some freedom for a different, more highly managed experience. EQ1 was designed around MUDs in spirit and the game really felt that way. And while things like sharing a dungeon with 30 other people led to TONS of problems, it also made for a dynamic, living experience. Basically no content was experienced inside a sterile instance and that gave the world a believability and life that you only really see in the "open" zones of games today.