if you can change the scenario in a detective show to make yourself the detective, why can't you change the scenario in a courtroom drama to make yourself the lawyer?
I'd imagine there are some folks who'd enjoy role-playing arguing in front of a jury.
I think the main problem is that being a lawyer requires too much specialized knowledge for playing lawyer to be fun. Being a cop or doctor of course also requires specialized knowledge, but you can pick up a gun or a scalpel, and the computer can be set to be more forgiving of your mistakes, at least until you get better, so there isn't any real barrier to newbies learning the game.
But how do you set a lawyer game to "easy" without it being obvious the game is rigged? Also, a cop or doctor (surgeon) simulation has a physical component, but a lawyer game doesn't. A lawyer game is just talking, and I don't know of a lot of popular online games that are talking.
Other than TrekBBS of course.