In the 1990s, it's OK to do comedy about the Chernobyl disaster or the Space Shuttle blowing up. It's acceptable to ridicule the Pope or the President of the United States, but God forbid you do a joke... about gays. The gay community is the last sacred cow in this society.
So many of these comics are just frustrated singers or actors - they want to get a gig doing a sitcom. It's paint-by-the-numbers comedy, lame joke-telling. They're drawn to it as a career move.