It actually it not useless, and considering it is a shooter based game, I should stay in game and be bindable as all buttons should.
The real reason no one uses it...
1) Hard to sneak up in people since headsets have good audio, and the Turtle Beach mics have actual legit superhuman hearing.
2) Melee without a knife is a joke when it comes to damage then again, knives are not all that better.
Personally I never Melee, but realistically it needs to stay in the game.