I'm coming from the 1NSANE community, where the track creations were alot easier since the game used a simple grayscale PCX for a height information (displacement maps from 3D world) and a colour PCX for a kind of surface and textures applied. The results were very simple compared to the pre-designed tracks like we got in LFS, of course, yet still there were outstanding user-made creations, pushing this relatively primitive approach to its limits.
I wouldn't be affraid of ugly, incomplete and, simply put, useless tracks. I would look at it as at skins making - tons of really questionable creations, but also few of amazing artpieces, which can compete with great default skins for sure. Give the people a tool to play with, you will be surprised how much time and talents they will put into it.