While I agree that comedy certainly stalled out around the '80s--almost everything settling into the featureless family sitcom or the Three's Company mold--I would consider it the peak of the cross-genre shows. I mean, what was Remiington Steele but a '40s romantic comedy written on Star Trek's "do what you can on this budget" playbook?
That's not to say that there haven't been highlights on the comedy landscape. I've enjoyed "How I Met Your Mother" for the nonlinear narrative and I'd certainly put "Sledge Hammer" in the same league as "Get Smart." But both of those also take the cross-genre philosophy to heart, too.
(I'd go back to the differences between comics, but I can't help think that'll just bring down my day. But I really do hate the constant backpedalling. "We changed the status quo! Uhm...but not too much. This guy is still around in a different capacity, see? Err...OK, we put everything back the way we found it. Because we meant to do it all along, though, and not because you were making fun of us on blogs...")