Rey just annoys the piss out of me because he's about as intimidating on the mic as a chimpanzee. That's really not the biggest reason I dislike people like he and Sin Cara as champions against people twice their size... it's mainly because of just that, most of the people they feud with are twice their size and the chemistry is just not there a lot of the time. Every once and a while they get in feuds with the likes of Jericho and Ziggler who are closer to their bill and both wrestlers can open up their arsenals, but when you bring in people like Orton, Kane, and Big Show, those matches are rarely decent.
I really don't think anyone who is poor on the mic should be a world champion though, that's just simply a deal breaker for me. People in that position get a ton of face time on Raw/Smackdown and it just becomes too hard to sit through.