Riley did interfere in the match, but not much. Even so, beating a 61 year old man is not that impressive. Besides, a great heel can actually win matches cleanly. Take Ric Flair in his prime (the 80s). Yes he did cheat sometimes, but he also won many matches cleanly.
I would not agree that he is one of the better wrestlers, his skills have improved but he is still not that good. I could think of at least 15 wrestlers off the top of my head who are better. My problem is that he does not have any credibility IMO as world champion. It seems clear to me that WWE just wanted to give him the belt to get all the media attention. Miz is a mid-carder who was basically made MTV Champion, there are other wrestlers who are more deserving to be pushed into the main event than him. Cena was right in the comment he made a few months ago that nobody considers Cena-Miz to be a WrestleMania worth main event and I don't see anybody buying the PPV to watch that match. I know it's probably my least anticipated match (I think Punk-Orton could be the best match). I don't hate Miz, I just don't think he brings any credibility to the title and don't think he deserves to be a main eventer.
As for Cole, the fans have never liked him. Even before he turned heel last year (which started during NXT season 1), the fans were booing him when he came out before the show started. The sad thing is that WWE likes him despite the fact that he is not that good of an announcer. He was not that bad on SmackDown, but he has become really bad on Raw. I wouldn't mind if WWE took him away from the announce booth and made him a heel manager.