Well that's the point. Technically I find UBB threads the best around. Is has (almost) all features a good messageboard software needs. If you take a look at vbulletin, you'll find that because of all the features, the admin interface is way to complicated. Most features in vbulletin are features you'll probably never use.
There is just very little modifications and good designs around for ubb threads. That makes it less interesting.
Also ubb.threads is missing a good import system. That will keep potential cutomers from converting.

Mike