I don't think it should be done. You often see it in boxing matches, however, I think it is generally used just to help the boxer get into his "groove," like when boxers punch themselves lightly on the chin to prepare themselves for the actual bout.
There is far better footwork in boxing, which involves less bouncing and a more stable stance. The only time you want to be bouncing in a boxing bout is when you are on the outside throwing jabs, and even then, it's just not an effective way to box.
Ignore the bouncing, take a leaf out of the great defensive boxers' book- upper body moving, bobbing and weaving- that's the more effective defensive movement in boxing. Bouncing is bad- when TKD guys do it it's bad, don't give boxers any more credit for it.