Well in Rex and Roxie the rigger and modeler were the same guy techinically. While I did design their look in Zbrush they were retopologised by the guy who would be rigging them with what he had planned for their rigs in mind. I agree that shoulder areas have been a big issue for us in the past and I also think this issue has been pretty well resolved mostly with the introduction of these two figures.  Here's a shot of James High Res - one of our most popular figures (often featured in TV shows like Bones for their crime recreations) and Ryan 2 high res and Rex.  All with their muscle morphs active (though Rex's is the new one I just made today).  You can see the shoulders on Rex look better than the ones on James and Ryan2.  Progress is being made I think it may be overlooked sometimes but it is actually improving.