Anybody who renders (either in Sketchup or outside of it) would benefit from stronger UV mapping controls -- Woodworkers (woodgrain on curved surfaces), Arch Viz (organic shapes) , Vehicles (more organic shapes), and even Film Production... just because they can kind of "get by" without does not mean it has no (or even little) benefit.
All the others I agree with more or less -- but I cannot agree about the UV tools as they are essential once you start applying textures to any flowing form.
I have suggested in the past and I still think it is the best option to simply move the UV editor outside of Sketchup proper in the same way as Style Builder works:
1) select any object you want to edit in Sketchup.
2) context click and select "edit UV mapping" -- which would launch the stand-alone UV editor.
3) edit UVs
4) save changed UVs back to Sketchup.
A simple workflow that any Pro user would accept and the nice thing is it never even has to be visible in Sketchup outside of one context menu command... Sketchup can work with UVs like this so updating Sketchup itself would really not be necessary at all.
Besides this is really not all that terribly complex of a concept -- it's essentially the same thing as skinning an animal... and we've been doing that since before we were "civilized".
Best,
Jason.