Why do sports get priority?

Last week on Sunday instead of playing a new episode of The Simpsons they have a baseball game, and on TBS there was a commercial saying that once the MLB games are done than regular programing will continue. Why is it that sports get priority over other stuff on TV? Why is it that people like me that don't particularly like any sports have to miss show because some game is on. I find that unfair. They should just find a time slot that isn't taken by a new episode of The Simpsons. A rerun of one of their other shows are fine, but not during new shows, that isn't fair.