I don't know that Detroit is so much more violent than other cities. It has had a bad press. Like anywhere else, one media plugged rape case or murder gives prominence to the idea that violence abounds.
It's true that many of the best restaurants are in Corktown, where you shouldn't walk after dark, but you can park easily so that shouldn't be necessary. Don't miss out on all that Detroit has to offer culturally because you are afraid of Corktown. Downtown is fine.