Easy answer.
DMC, God of War, Heavenly Sword.... already got the market for such games. Sometimes games just need to feel different. Bayonetta by the commercials looks like DMC. So from a casual consumer why would a DMC fan buy a game they already have?
Squilliam: On Vgcharts its a commonly accepted practice to twist the bounds of plausibility in order to support your argument or agenda so I think its pretty cool that this gives me the precedent to say whatever I damn well please.