I was thinking that it would be nice if there were a trilogy of 4e CRPGs, broken up right along the tiers, where you would get to transfer your characters between them.
It would of course mean that you spent a lot of time at any give level (at least if the games were of appropriate length), though with how 4e works that probably would not be too much of a problem. And it might, you know, mean that some thought would have to be put into the role-playing elements, and having different kinds of rewards other than just experience and loot.
I think reputation could play a central role as a mechanic in such games, which each NPC having their own reputation meter than you fill or take from based on your deeds and actions. So, helping a town would improve your reputation among most of the folks there a fair amount, except for the connivers who want to see it suffer, and among the neighbouring towns who trade with it, but would hurt it a little if your aid hurt a competing towns business, except for the families there who have relatives in the first town, and so on.