Machida uses karate, but has a black belt in BJJ....He's also sumo wrestled and added in elements of kickboxing to his striking style....the way he lands some of his kicks is proof of this.
Chuck developed his punching game more and has since added in elements of kickboxing to his style as well. Lots of MMA fighters have karate as a base....GSP, Anderson Silva, etc. It's a base, but what makes great fighters is their ability to add to that base and take elements of other styles that work for them.
Anderson Silva started out as a TKD black belt, then started practicing muay thai like crazy.....he worked on his hands and focused on boxing (fought professionally as a boxer and a muay thai guy)....then he added the black belt in BJJ. Add in the god given gift to best a quick, graceful fighter and that's why he's a monster in the cage.