Personally I think the striking and TDD is better and these rankings reflect that.
Maia, Sonnen, and Okami were almost entirely grapplers. Picture them in a kickboxing match. There are not as many guys like that today.
Because TDD is better you have to have striking.
But I don't think the new MWs are better athletes or drastically better, just a bit different.
A very good striker in the past who would get murked by Sonnen or Okami via wrestling would do better today as they could learn TDD/BJJ easier.
Someone like Bisping who was reasonably well rounded with a great gas tank is about the same in either era. He beats 3-4/10 guys in the top 10 in either era.