But the paradox is that Williams, Carrey, Martin and Hanks have all excelled in DRAMATIC films as well.
Agree with Williams, Carrey, and Hanks (and add Murphy and to a lesser extent, Sandler), but what dramatic roles has Martin done? I can't think of any.
In any case, I do get the feeling that Williams, Carrey, and Hanks (and maybe even Murphy), have enjoyed going dramatic. Hanks has pretty much entirely shifted to dramatic acting. So that's another thing. Even the comedic actors get tired of doing the same kind of comedy over and over again.