The folklore I heard with regards to high spring tensions on Campag and similar brake calipers was that during the heat of a race everyone is amped up and muscling their bikes through the peloton and corner and down hills. The spring tension was high so you wouldn't grab too much brake at that point in the race, and slow down too fast. Your body was at it's peak and a lighter feeling spring tension would feel too weak and you'd over-compensate.
So why do roadies have such skinny arms?
Tom Martin
Oakland CA