It is a fact of physics...larger area has more clamping force with the same pressure on the pedal. It means that the experienced driver will not have to mash the pedal to slow his rocket from 100+ mph. It has the added benefit of cooler surfaces due to less brake applied time. It also can indeed lock them up quicker. (see above, EXPERIENCED Driver) An ABS System pulses somewhere about 10-15 times per second. Even in some of the best systems, momentary (reaad that as fraction of a second) brake lock is common. For the average driver in a slightly modified car they are not totally necessary. It is almost more for asthetics. Large open wheel, Tiny rotors and calipers... I will agree with the tires greatly affecting braking performance. Redneck slicks (Lots here in VA) on dry pavement will stop faster due to more contact friction. Doesn't work that way in wet conditions. I guess what I am trying to say is that a larger brake system is not a waste. Done properly, it can be a valuable upgrade to any vehicle. Done wrong and you will be all over the road, in or even under somones trunk.

:cheers