I would be in favor of dropping a few worlds...even if I'm in one of them. A longer term approach, but might be effective would be to eliminate new signups for those worlds.
Having now played at D3, D2, and D1AA, (also with some co-coaching at D1A), there is clearly a difference among those levels. In my opinion, it appears to be a pretty good building block approach to learning the basics of the game, learning how to recruit the players that fit your system and that will perform, to how to get to the playoffs and be competitive with other humans, and then finally how to put it all together in order to make a run at the top 10 and a major bowl game at D1A.
I also like having long term coaches at each of the levels. It gives everyone a "target" to hit. It shows coaches at each level where their program needs to be in order to be considered competitive for a national championship. There should be "dynasties" at each division. In Wilkinson D3 there are a few teams that "rule" the division. Bluffton, Baldwin-Wallace, Utica. A few others challenge regularly (Menlo, McDaniel, Anderson, MacMurray, St Olaf, Rose-Hulman, Colorado). There is your regular top 10 for the last 10 seasons or so. Menlo just changed coaches, Colorado has undergone a few coaching changes. The others are almost all 20+ seasons at the same school.