Trace always seemed like a good guy, but ended up getting screwed pretty much by Mallon after the movie flopped and probably didn't get that much income out of the whole ordeal. Frankl's a real bastard, so screw him if he's broke.
The show didn't really lose much when they left either. The mad stuff was always my least interesting part of the show, especially after Joel and the invention exchanges were gone. They didn't let the guy from the first eps, Weinstein as Trace's sidekick last long at all, and he was indeed annoying.