My biggest problem with MMA is that while technique helps a fighter, I think it's the kind of sport where a meaner, tougher, and more athletic athlete can dominate. Look no further than UFC:91. Couture went in with a good game plan, wear down a guy who out-weighs and out-muscles him. He kept him away with boxing, and made sure that he always controlled the clinch. He even had two great escapes from bottom, but under Brocks weight it ended up wearing him out. He went in with a great game-plan, he was just not as mean/big as Brock.
I love watching boxing. I think as a sport it requires much more technique, and I feel the same with any pure martial art. But when you get into MMA I think it's far too easy for one tough SOB to out-fight a brilliant tactician. Pride and honor aren't necessarily good qualities to have as an MMA fighter, wanting to hurt someone is. And that bothers me, because in most martial arts the first thing you learn is that you're learning a martial art so that you can come up with other ways to resolve conflict. In MMA you're trained to attack someone when they're on the ground, and give no quarter.
I do enjoy watching it. And I do enjoy watching experienced and talented martial artists in the field. But the thing that bothers me about MMA is the crowd's blood lust, and lack of respect for the arts involved. Certainly the average fan knows a good amount of technique, and call each move when they see it. But I think for the average viewing they're more drawn for the blood shed and guys hurting each other more than the incredible technique and spirituality that can be drawn from each art. It's not that I dislike the sport itself, but I think the very nature of the sport keeps the average viewer from seeing the forest for the trees.