Apartment complexes seem to be really popular places for car thieves, no matter how nice the place is. This particular apartment complex I was in was particularly shitty (I had just graduated college in 2009 into a recession economy, so my housing budget was particularly tight), but I've had cars broken into in the past while living in much nicer areas.
Kinda makes sense if you think about it though. At a place like a mall, you have people coming and going all the time. At apartment complexes, you have the same wide variety of cars to choose from, but it's a pretty safe bet that few people will be around since you can go through them while most are asleep. Very few apartment complexes have much of anything for meaningful security. Gated communities give the illusion of a secure area, but add next to no security at all since everyone just tailgates the person in front of them to get in and walk through gates are constantly propped open for people who forgot the code. If anything, a nicer area probably just means you have more expensive cars to sort through.