Lots of worlds fill and roll. Many of them sit and don't fill/roll. It's only a problem for the people in the worlds that don't fill. Personally, I wouldn't stick around in a world that has trouble filling, and I'm either lucky or smart enough to be in good worlds. I don't see the new worlds as being so much of a problem, because many (most?) of them are heavily themed and rule laden worlds that don't really fit in the same category as many of the worlds that have trouble filling.