What would your ideal MMOG be like?

Make it so that everything put into the game has value and cannot be "pick and choose"'d down to the most efficient path. You could choose to explore areas at your own pace, and while actions you take would have an effect on the world; reactions within the world would not eliminate overlooked prior exploration opportunities.

Thats pretty hard since at most there would be several efficient paths but it wont be without the "most efficcient path" thing since unless the game changes way too fast people are going to notice them and tell others.