My take:
When you throw the ball out there wide, the safety has time to close some of that gap. For the play to be successful, both WRs have to succeed in their blocks and we have to beat the safety (not impossible, KU did it to us their first 2 drives). My concern is if you're under center and end up throwing it backwards, it could be a fumble thats just lying out there to be scooped.
I just think its high risk-low reward. Usually you get 4-6 yards maybe. If you screw it up, its incomplete or a fumble. If its incomplete, the clock stops. Running can get you 4-6, low risk, and the clock runs.