But that's just it. These people are better mixed martial artists, rather than masters at a specific craft. Anderson Silva was a wonder to behold, but he was also fairly one-dimensional. Once he ran into people who didn't blindly chase him and could wrestle, he was in trouble. So Whittaker/Rockhold/Weidman may not be as spectacular as Silva, but they're better fighters all-around.
Another thing to consider is that as the talent level grows, fighters can look more mundane because there's less of a gap between them and their competition. It's why fighters often go on a finishing streak on their way to a title shot, then once they have the title, they get "boring." Sure, part of it may be playing safer, but another substantial part is that they're now consistently facing the absolute best in the world.