The problem is that Americans are pretty insulated from other cultures, even ones that speak English. Anytime something even remotely interesting is created outside of America, the first thing the American broadcast companies do is remake it using Americans and Americianisms. So the viewers there never experience any real variety in their shows. Most of the time these remakes just don't translate that well. Some TV shows are brilliant only in the context of the country they were originally made in. British humour (and Australian too at that) commonly uses wordplay as its main method. Where as American humour uses visual metaphors and is very politically correct. British shows use an icy cold wit, that doesn't shy from any topic no matter dark, that can completely go over the heads of under educated Americans. As for irony. this seems to be a completely alien concept to American TV. What Amercans need to do is widen their horizons. Go watch a French comedy with subtitles. Watch the ultimate British comedy, Fawlty Towers, and learn what funny is.
As for drama, the Brits had this guy, William Shakespeare, that pretty much invented the whole idea.
Some American shows that "get it right" in drama or comedy:
Big Bang Theory
Hart of Dixie
I Love Lucy (Slapstick is what Americans do better than anyone).
The Good Wife
The West Wing
The Odd Couple
Mork and Mindy
Everybody Loves Raymond
Dallas (original and remake)
Shows made outside of America that "get it right" (drama or comedy):
The Office (British version)
Kath and Kim (Australian version)
Wilfred (Australian version)
Doctor Who (Britain)
The Bill (Britain)
Inspector Rex (Germany)
Monty Pythons Flying Circus (Britain)
Some American shows that don't have a clue:
Kath and Kim (American version)
the Office (American version)
Saved by the Bell