James,
My proposal would give B more protection from contact, but the trade off is that the receiver will have be good enough to ignore the 'presence' of an opponent. If the A player gets bonked on the head, back, abdomen or legs by the untouched kicked ball, then we've got illegal touching, anyway, so no big deal. Chances are, if he is so close to the receiver as to get bonked by the ball, he will probably contact him, drawing the KCI flag. We use the catch criteria to establish when the receiver can be contatced, i.e., the receiver has to do something with the ball after he catches it before he can be contacted. If we don't have a catch, and we have contact , its a KCI foul. If we have a catch, then we can't have a KCI foul. If the receiver has to go through a defender to get to the ball, then he gets the KCI foul. That'll make the defenders keep their distance. If the receiver chooses to run around the defender, he gets nothing.
Much simpler, and more fair to both teams. IMHO.