So you don't go whistling off the end of the runway. Energy is proportional to V Squared and so every knot you can lose airborne, is energy that doesn't have to be dissipated by the brakes.
You have committed to land and so do not need to fly at Vmcl-2 which would maintain your rudder authority in case you have to power up. If you do try to do a MAP, having already commited and slowed to Vapp, you can forget about seeing the chief pilot for tea and biccies; you'll be eating asphalt!