Allowing comments in the gallery entries would allow for criticism. Not that critiques are bad, but I appreciate the fact that Moi3d's gallery sits as a simple testament to MoI's ease of use, even for design newbies, because they especially should feel pride for what they were able to create.
Plus, I bet that would add a level of complexity to the site.

Maybe a fair idea would be for someone to start a MoI3D group on DeviantArt, where you can post comments and be in effect a beacon to attract other (more art-centric) designers that would have never noticed Moi within their sphere of influence. That's not a bad idea, but we'd have to find someone willing to moderate.