The "problem," I suppose, is the proliferation of content because of cable. Cable, of course, has led to a number of great shows, but Sturgeon's Law still applies. And since there is a lot, LOT more television now than in the three network era, ther is a lot of crap.
Sure, but that has always been the case, even back in the 60s and 70s, a lot of the shows were garbage and there were a few good ones. But the fact is there is quality TV content now, then in the past, one has just has be discriminating. TV is way better now then it was in any past decade.
With so many more outlets, we have more avenues for good shows to be created, then in the past. TV can get away with things that you could only do in movies in terms of mature content and all the cable channels have produced a wider variety and diversity of shows, that would not have been possible in the past.
I think anyone who says TV is worse now, then in the past, is mistaken and is not looking in the right places.