As I was getting out of my car just now in my parking garage I remembered when I had my car broken into some years ago. Among other items they took a valet key that I had in the center consol. Needless to say I had to disable the car (by taking the distributor cable off the distributor - remember those

). I soon changed the car anyway so it wasn't an ongoing issue luckily.
Even though our doors can't be opened unless unlocked, a broken window and a quick check in the center cubby box or the glove box could easily reveal a key left there. Then the locks would have to be changed - if they didn't drive it off with the car at that point. I don't know if insurance would pay for the lock change.
Just a thought.