Well we all have different tastes, but in no way would I consider a show like Damages, or Rescue Me geared toward a 3rd grade mentality.
Sure, there were some good shows in the past, but to me today's stuff is better written, free from the limits of broadcast restrictions, have higher production values, and often better acting. True there is a lot of crap out there but there are also hundreds of channels to fill. To be honest with the limited number of channels back then the quality should have been higher, but Manimal?
Competition has served us well. You could not conceive of a show like Weeds or Jackie even 10 years ago, yet Weeds is in it's 5th or 6th season with a skewed world view, True Blood is taking off quite strongly, and lets not forget a show like The Soprano's. They all have strong fully developed characters and well though out plots.
Trying to compare a show like The Soprano's to a show like Dallas, both soaps in a way, is like comparing a Nancy Drew to some of the stuff by Elmore Lenard - sure there may be a who-done-it, but that is all they have in common. Some of it stems from the difference in broadcast vs cable/SAT, but a good plot and good story telling can be done on broadcast tv, but it's not. Compare a procedural on any of the broadcast networks to a show like Saving Grace, sure they are cop shows, but Grace has a lot better sense of reality to it.
I can't think of too many broadcast shows other than Lost that keep you thinking. All the CSIs are there just to show gore, House has devolved into the illness of the week, Bones has turned into Moonlighting, and so on. At this point there is nothing on broadcast that I would put up against the stuff on the basic tier of cable/SAT. Why do you thing NBC stripped Leno 5 nights a week?