The sportsbooks should stick to the core business of SPORTS! The crazy props about weird events like which player will score first used to be restricted to highly analyzed games like Superbowl. Now, you can find these bone-headed props evey week.
Betting on the outcome of trials is fairly low-brow. If it was your family member that was raped/killed/etc, would you want some sleazy sportsbook trying to make money taking action on like it was some game?
However, I hope that the owners of sportsbooks that post Kobe Bryant and similar trials wind up on trial themselves, so they can see how they like it. (Though most of the scum I've met would try to bet on the outcomes of their own trials to cover the legal costs.)