Oh, come on. Cliffy B. has dropped a hint that JJ3 may be a future game, and Noogy is working with Cliffy on some project. I think that is enough to turn from your doubts.

....HAHAHA, I just called him Cliffy! Hey, that is HIS nickname, not one I made up.

And about level editors. Pre-made geometry can make level editing much easier. Want a bridge? How about an arch? *click click* and POOF! You have an bridge or an arch. Perhaps even a hillside or a building can be pre-made. Have you ever played .Hack or Dark Cloud? Both have dungeons completely made of pre-made geometry that is used over and over again (No, I'm not saying that is a good thing, because I think it stinks). However, a person could decorate the rooms differently enough to make the pre-made rooms look unique. It is somewhat like using a tileset.