I think the knock on these rankings is more that they don't always show what the "best" schools are, really what they're more useful for is publicity. Sure, it gives a pretty close reading, but if I'm going to school for engineering, I'm not going to go to the #1 school, I'm going to go to the #5 school. If I'm going to school for film, I'm not going to go to the #1 school, I'm going to go to the #25 or so school. Nonetheless, great for the university.
I always get a kick out of the notable alumni section at my school, BU, when they list Bill O'Reilly next to Howard Stern. Opposite ends of the spectrum there, to say the least.