The problem isn't too many mouths to feed, the problem is Dez Bryant. There is a reason that the Cowboys have Dez followed by a 24 hour security team so that he stays out of trouble. The reason Romo targets Witten and Miles over Dez is because he trust that Witten and Miles will be where they need to be. As we saw with the pick 6 tonight, Dez has poor communication with Romo.
I will say that it bodes well for Dez that Romo came back to Dez a few times after that pick 6. There is no doubting that Dez has the physical tools and is a great situation in a pass-happy offense where he could be a top 5 WR. The only thing holding Dez back is Dez. That is just the risk/reward that you take when drafting guys who have history of off-the-field problems like Dez, Marshall, Lynch, etc.