This may just be old man nostalgia talking, but at least part of that spark feels like its gone because the genre became too popular and information flowed too freely.

One of the things I distinctly remember about older MMOs, especially Pre-WoW ones, is how so much information was basically just passed on from player to player. You’d join a guild, because the guild forums are where you could post maps and strategies and the like. But your guild forums were also mostly just private to you, so useful stuff could take a long time to leak out.

With the rise of wikis and big, well connected social communities, a lot of the exploration element of the games is just theme park rides and the mechanical experimentation gets analyzed to death in the first few days because of how collaborative everyone is instead of everyone being stuck in smaller groups with non-perfect info.