Why fouling is NOT a good idea:
1) There's a chance the opposing player gets THREE foul shots instead of two (this is the obvious one). It can be player savvy (knowing the foul is coming and hoisting up the shot), a bad call from the ref, or a stupid blunder on the defender's part.
2) There's a small chance of facing the worst case scenario of a potential 4-point play, losing the game altogether with no chance of overtime.
3) If you foul, and the 1st FT goes IN, but the 2nd FT wildly caromes off the rim (intentional or not), there is a very real chance the rebound will wind up back in the opposing team's hands. Now, they can WIN the game on a 3-pt shot, or tie it up with a quick putback.
So why foul?
Great defense wins close games period. Relying on Vin Diesel's logic "it don't matter if you win by an inch or a mile, winning's winning" will not get you very far.