Before I go on in this argument, lets get something clear:
1) Hitting an area where your weapon bounces vs hitting an area where you weapon doesn't bounce = no difference in damage? If this is your argument, then I do not believe it to be right.
2) Hitting an area with a weapon that bounces, vs hitting the same area with a weapon that doesn't bounce (weather it be with fencing or increased sharpness) = similar damage? If this is your argument, you are most probably correct.
Damage formulas are based on the weakness of the part being hit, and in every one of them, if you focus on getting the weakest area, the monster will consistently go down faster, than if you just strike at whatever is closest to you at the moment. - This is my argument.
Bounce or not, if you go after a weak spot, with the exact same strike vs going to a spot where you CAN bounce off, even if you don't, will always mean you are hitting for much less damage.