That's not a bad idea. Though I think they should continue to count incompletions and interceptions against the quarterback (and I'm a McManus fan!) because if you stop doing that the future QBs will appear to suddenly be way better than any of those in the past.
BUT maybe they should start keeping track of dropped balls by receivers. Just like a completion counts for the QB and the receiver, a dropped pass counts against the QB (as an incompletion) and the receiver (as a dropped pass.) An interception off the hands of a receiver would count against the QB (as an interception) and the receiver (as a dropped pass.)
BUT the problem is: how would they determine whether it was a "drop" or just an incomplete pass? If a receiver is triple covered, leaps 6 feet into the air and gets both hands on the ball but fails to come down with it, is that a drop? What if he catches it but comes down out of bounds? Which player do you blame that on? Who makes the determination?
And why does a QB get credit for a touchdown pass when he throws a little 2-yard out and the receiver breaks three tackles, hurdles another, spins off another, outruns two more, straight-arms one, and drags 4 players 10 yards into the end zone? The receivers could say, "If I'm getting blamed for dropping a pass, why does he get credit when I do that?"
Now that I think about it, maybe it's not such a good idea after all.