I think a good alternative to questing as it currently stands is to somehow tie exp and/or skills to achievements.

This way you get the people who like grinding to unlock the x amount of mobs killed achievements.

This also forces people to experience all the content that an mmo has to offer. Or if there was enough achievements players could choose any method they wanted to cap on levels or do any combination of it dependin on what kind of content they were in the mood for that day. Thoughts?

It would obviously have to be balanced and difficulty to exp ratio would need to be appropriate.