Hmm, hmmm, hmmmm, what do I say, that we have too much comedy on? May upset some people, but I think it must be part of the problem, if indeed it is deteriorating as I believe it generally is.
The more channels we have, the more new comedy progs get poured into them and the quality of these ain't always that great is it.
But you take the best comedy from any era, and I'd say the best now compares relatively okay in quality from past decades, just not in content. Content has changed a lot. I think scripts have got cleverer, but coarser at the same time.
There are some good late night sitcoms on, but I think the really popular, funny, peaktime sitcom has suffered drastically, it's almost been neglected now in favour of BBC Three type young audience sitcoms or the tsunami of trendy US comedy star led copies. Which depresses me on several levels.