Well im just an inexperienced end-user... I don't work in the field, know anything about programing, and I have a hard time understanding the terminology of the 3D industry.
Im more of an
ArtRage man myself
So with that out of the way... my $0.02:"Refining and exporting meshes" would be high on my list. As I would (and have) used shapeshop to make a few models I rendered in Kerkythea. Jagged edges in a pretty render is undesirable.

Likewise the opposite is true, a small mesh really helps if I were to ever run the OBJ export through Pepakura to make a papercraft model. As Pepakura can only handle smaller polygon counts (and it makes it easier for gluing).
Other feedback:a few simple tools for drawing... I know, the current drawing method ROCKS MY SOX!, I just wish I had some kind of straight line tool, circle/square/etc that could make a few things a little less "plush" looking

(I really don't know where I am going with this one...) it probably already exists (I just haven't looked through the program as extensively as I wish). I find using a real-life ruler with my tablet helps

The texture export has very little impact on me personally... I never really knew how to do that kind of thing in the first place. When people say things like UV, etc. I think of sunlight outside. I guess I am more game for running it through Kerkythea or Photoshop to texture a model that I make (which is kinda rare these days).
A "new" or in your case "delete all hook" would also be nice, for those more finer moments in life when you get frustrated as all hell and just want to start over (without having to close and reopen the program).
Final Thoughts:I think a Beta would be a good thing. It shows us that the program isn't dead or stale. It also allows us to find more bugs and point them out in the forums

I finally got every Saturday off this month and I plan to sit down and thoroughly go through ShapeShop. After I do that maybe I can provide more information to this discussion... this is just my immediate feedback.

-Keith