Originally Posted by Gibonius
Anywhere else on the field, a ball fumbled out of bounds just goes back to the offensive. The touchback in the end zone creates a big incentive for the defense to just let the ball go out of bounds, or encourage it to do so. Makes it way easier for the D to recover fumbles in the end zone, which is probably not intended by touchbacks rules.
I've thought about this, and I don't understand why there is an exception to the general rule that a ball out of bounds reverts to the last team to possess it. Why not give the ball back to the offense on the 20-yard line with a loss of down? That seems to be a significant penalty, though not a draconian one.