Why have so many America shows got a dark subtext

Modern American shows seem to have such a dark untertone.

For example

Lost - couldnt just be about a small groups survival on a deserted island before some sort of "Lord Of The Flies" tribute starts playing out, but with the whole 'others' thing and what-not it got really dark.

Desperate Housewives - couldnt be just about a close knit group of friends and rivals from a neighbourhood but had to include past murders, baby-napping and stuff like that.

Ugly Betty - couldnt just be a run of the mill "its whats on the inside that counts" rolemodel program for young women and older ones aswell but had to have a dark subtext!

Why can't there be dramas without random, suspicious and sometimes disturbing backgrounds :? 

But people watch those show. So maybe its good that way?

To stop them being run of the mill? Because making it dark obviously makes it much more exciting, so more people will watch it.Snomel

A "Lord of the Flies" rehash wouldn't be dark? O_Oxaos

He was comparing it to Lord of the Flies being dark. It was worded awkwardly.