Since the 80s, corporate America has held too great a lock on the media. And, until we see some strong, unified grassroots efforts in this country, I don't think we're going to see much in the way of cultural development (be it in the form of music or cinema, TV, fashion etc...) Big industry doesn't want to speculate as to what people will or will not like, and thus recycles the same stuff over and over, each time marketed in a slightly different manner.
Perhaps the only redeeming aspect of the current media culture is that is has served to increase the longevity of stars, allowing us to see familiar faces evolve/expand over time.
I should say that there have been some really powerful films with "serious" subject matter in recent years (mostly foreing/low-budget films, but even a few from Hollywood), and there's no doubt that films have become more visually impressive over the years.
However, I totally agree that Hollywood has really lost the magic when it comes to comedies. Everything I have seen in recent years has come across as being "forced." There are usually a few good jokes in each film, but these are dilluted by too much vulgar or cliched humor. It seems like the films try and do too much...throwing in too many elements and therefore wasting opportunities to build on/carry through earlier themes.
If a really good comedy comes along, I'll know to rent it when it comes out on video. Otherwise, I won't even go and see a comedy in a theatre these days (well, unless I have a date
The best films/music etc... come out of times of social unrest, and that's one reason why I feel the 90s was on the whole a very lackluster decade in terms of pop culture. There were certainly a lot of people with things to say, but there weren't many unified movements. The corporate media dominance often silenced those with new ideas, or forced them to resort to compromised/distorted means of conveying their message.