That's standard for prosecutors, especially when they have a middle-class defendant who's family would be financially ruined by legal fees if the case went to trial, and whose life would be effectively over if convicted. They go for murder-2 and say they will allow a plea of manslaughter with under a year in jail.
In civil suits there is a "loser pays" provision in some states, to minimize frivolous actions. The same should apply to criminal cases, so the cost of defense doesn't break the innocent.
Rethinking that principle, though, OJ's defense costs would have had to be paid by the state when he was acquitted. I don't like that idea so much.