Board Thread:Questions and Answers/@comment-5628819-20130120232222/@comment-5618441-20130122143905

An Arrancar (破面 (アランカル), arankaru; Spanish for "To Tear Off", Japanese for "Ripped Mask") is a Hollow that has removed its mask and has gained Shinigami-like powers.

Tite Kubo didn't invent the concept, yes thats true, but could it also be because Ichigo broke it with his Zanpakuto? Rukia said that Soul reapers normally don't attack the face of the beast because that usually happens.

I like to think alot, but its probably for the reason Godisme said.