I think it's because of the fact that generally MOST of the SWTFs have awkward, poorly proportioned robot modes. As robots, I think they're both ugly, and inconsistent with TF aesthetics. The Turbo Tank and this shuttle are a couple of the only exceptions I'm aware of. zmog
I know what you mean about proportions, believe me, I originally HATED the SWTF line until I actually bought the shuttle (cause its alt mode is one of the best Imperial Shuttles made so far in my opinion!). I think it's a matter of using the mold as a base and seeing the potential for a non-traditional TF to create an original looking TF ; for example, with Tiin's Jedi Starfighter, you've got a really slick looking Alt mode (ignoring the whole circle attachment that's rather ungainly) that's really compact and would look quite detailed when repainted. I think I'm going to change the head entirely, bulk up the arms and have them fit in the alt mode by sanding the bottom sections in order to make more room, and maybe even reshell the front section that transform into the legs in order to make them a bit bulkier as well. After all, look at this Sideswipe!