Artists throughout the ages have deleloped and sustained styles that work for them quite well, even over the course of many years. Writers and painters, for one, have successfully done this for thousands of years, and this has done no dis-service to anyone. Indeed, would we even know Monet if not for his impressionistic style of furious and thick, though controlled, brush strokes? Would we know Hawthorne if not for his fictional documentation, and seeming obsession, of the secret sin that lives within us all?
Of course, as Tom Doak has mentioned, perhaps this may not work so well with golf courses, as each site is different, and might therefore be treated different, unlike the same-ness of blank pages or canvases of the writers and painters.
But, like he also said, it is every designers prerogative to stick with a given style, or to branch out. And further, I don't think either decision is bad. Let them make a hundred courses that feel the same, if they choose (and, more importantly, if clients desire them to do so). They are entitled to make a living, so let them do what they are good at.
But, we also know that there are a lot of other designers out there who are doing different things than him, and therein lies the diversity. The differences may not be within each individual designers work, but within the entire profession, there are nuances enough to provide for a wide range of golf experience. Maybe that is what should be celebrated?