In the video posted before (365 days of a bike) it was interesting to see how after the obvious (loose/easy to steal) water bottle, basket in the front and the saddle the lock is among the first things to be stolen!

Or maybe they just took it off because it was worth more then the bike.
Once the tires are empty and the saddle is missing it goes faster and people start to feel like it's ok to take parts from this bike...
I agree that lock picking a bike lock is pretty rare. Brute force, even with power tools and such, in clear daylight, with a lot of witnesses doesn't seem to be a problem.
http://www.youtube.com/watch?v=UGttmR2DTY8Would you get involved if you see someone doing this to a bike that is not yours? Really?
I did the same thing once with a motorbike (that was mine). We used the electricity from a nearby shop and a power tool. Lot's of people looking at us, but once you look back they quickly walk on. Yes, this was many many years ago. Nowadays I would have taken the time to open the lock in a non destructive way.