What does BDSM have to do with it? I don't practice BDSM, yet I cannot imagine having sex without me and my wife saying the word cunt several times. It's just a good sex word like cock, pussy, snatch, dick, pecker, twat, beaver, and tallywhacker, among others.
In fact, 'cunt' should be yelled out loud with great passion while fucking, pulling hair, and butt slapping.