There should be no grinding at all, questing or otherwise. In my ideal MMORPG, there would be no levels at all, and it would be about the journey, not the destination. One of my biggest peeves about the genre (and some games that are copying it) is that they seem to feel that a fake sense of accomplishment is more important than actually having fun along the way. Korean-style MMOs are the worst offender of this, but almost all do it to an extent.

I'd much rather the progression path consist of actual achievements, rather than some arbitrary system like we have now.