I don't think so.
I think that the level of athletes competing is rising, and because of that you're getting more and more guys who are extremely "cut." Basically, if you train regularly and eat well, you'll be in good shape. But, if you train insanely hard and are very picky about what you eat, you're going to come out extremely cut. Basically, the harder you work, the more your body is going to reflect that. Now that the UFC is bringing in more money and popularity, guys are working harder to be the best they can and therefore look more buff.
But, I don't think the UFC is recruiting based on looks. Different guys shape up in different ways. Some guys get the chisseled look to them, while other guys get "loaf" style muscles that aren't impressive to look at but are very strong. Just look at Fedor - You can tell he's in shape, but he's not impressive to look at. But, get in the ring with him and you'll suddenly realize just how strong he is.