I can't think of a reason QR is better other than price. I actually find it easier to mount and unmount the wheels with thru-axle. They're not really permanently installed though, so they can be stolen if you know how to take them off.
Anything can be stolen given unreasonable dedication, but that's not the point. The point is to deter by making it not worth messing with. Unlocked QR wheels will be stolen or vandalized in most major US cities in an instant.
When I was in college, I'd pop the QR front wheel off and chain lock it through the rear wheel+frame+rack. Only took an extra 10 seconds or so, and took less time than it'd take to lock two chains to make sure everything was secured to the rack.
