Why are modern shows so different from decades ago?

[x7q3]

In the 90's, I remember how there used to be good half-hour comedy shows. These shows actually made you laugh. Shows like Saved by The Bell, Step by Step, Family Matters, etc. Now days, they have comedy shows, but they aren't funny.

Shows used to have catchy, memorable theme songs. I'll just go ahead and use the above shows as examples again. Each of the above shows has a catchy, memorable theme song.

With modern shows, there is zero theme song. There are too many actors on one show. With dramas, the plots are overly complicated, and go in too many different directions, with too many people talking about different things.

Decades ago, there were few actors on a show. There was a simple plot. There was a memorable theme song. These shows were fun to watch. Today is pretty much the opposite of all that.

Here are more shows I like: Three's Company, Gilligan's Island, Cagney and Lacey, 7th Heaven, the original Twilight Zone, Walker Texas Ranger, Hunter, Xena Warrior Princess, etc. I noticed most of these shows have things in common: a memorable theme song, few actors, simple plot, etc. They are fun to watch and don't take themselves so seriously. Modern shows, like Game of Thrones, True Detective, the new Twilight Zone, Westworld, The Blacklist, etc, are so serious that they aren't fun to watch.

How did TV change so much? Why do they have no theme song, too many actors, overly complicated plots, etc? Modern shows are impossible to watch, for the reasons mentioned and more.