Hmmm...
I concede the point, our current setup is optimal. At the outset, when only a few players are eligible for creative, the creative world would be fine, but as more people earn access, chaos would reign. When we take time frame into account, this is the ultimate truth.
So, I now declare myself in favor of keeping the current setup, 1 peaceful survival, 1 mob survival, and Hoenn as a projects world. I think allowing creative in Hoenn would be nice, but I also think it should be closely controlled, and whoever elects to do something there should have a clearly defined plan. The best way to avoid clutter is to reign in excessive experimentation.
Also, for the Survival world, I vote that the only structure we place in the world be a small shack housing the return portal. Let's leave everything else to player agency. I intend to start a fully legit survival town, or hopefully a city, with the end objective being an epic odyssey through Hell, to the End, and back again (preferably with airships).
And as for new-player zones, I totally agree. I think we can use WorldGuard to enforce this.