People make fun of me for carrying my laptop with me everywhere. While it's a hassle, it beats the alternative of potentially having my laptop stolen. Not only would I have to get another laptop, but I'd also need to change all of my passwords, revoke my SSH keys, and hope that I had recently backed up my data.
Unfortunately, car break-ins are on the rise and many of my friends have been victims. At times it seems like thieves are indiscriminately breaking car windows just to see if there's anything worth stealing. So, keeping your laptop / bag out of plain sight doesn't substantially mitigate your risk. While you may feel like it's unlikely to happen to you because you've parked in a "good" neighborhood, I'd urge you to take your bag with you. The convenience isn't worth the risk.