Hell, the roster's stacked now, but there's no direction as to who should be a part of which card. Yeah, the smarks can tell you who the ME, Upper, Mid and Low cards should be, but it doesn't look like the WWE knows that or what they want the shows to be. Smackdown used to be upper midcard transitioning to ME back to Raw(or overexposed ME's needing a bit of a rest to get fresh)/midcard/tag teams/cruiserweights/developmentals, while Raw was ME's/Upper Mids/Promos/Divas. They have the roster to still fill all of that, but since they haven't been really pushing anyone except for their new promotions from NXT, they don't know where everyone will fit and lots of talent is still very mic-untested. This is the problem. I always hated the separation, b/c I wanted to see some stars on both shows, but right now it is NECESSARY for development.
I think another thing that happened was since Smackdown focused so much on wrestling, primarily for development, Raw kept snatching all the good talent, and then trying rotating them to fill both shows that eroded and then killed both brands, as less and less airtime was being given to keep developing. This is also something that really needs to change. Stick to what you do best, but find out permanently what you do.