Sorry to see but not surprised anymore to hear of these accounts. That might be worse to come back to then a smashed out rear small window (which happened to us). In your case I'm sure it wasn't the frunk they wanted to get into, but from what I've read of other people's accounts of missing bumpers it was your car part.
Auto break-ins and vandalism are at record levels around here. I suspect it's to fund drug habits for quick cash. I don't know when there's going to be a real crack down on this activity and can't believe given the statistic around the bay here that this hasn't been given some area-wide priority. Here's a few recent articles from around the SF area but you can almost search a city name and car break ins and come up with similar stories: SF -
SF vehicle break-ins at record levels; police try new approach ; Lost Gatos -
Los Gatos: Lock your cars, auto burglars are on the move (yeah like that helps); San Jose -
Rash of car break-ins plaguing San Jose residents
And we wonder why our auto insurance will probably go up.