Yet another reason why it's good to practice unclipping both feet... a tale from the file of stupid things I have done:

A few years ago on my short but hilly lunch time ride I started hearing a "clanking" noise while pedaling. I couldn't visibly see anything wrong and nothing felt loose so I decided to keep on riding. About 5 minutes later my left crank came off entirely, but was still happily attached to my foot. It took a few panicked moments before I could get enough leverage on the right side to unclip and stop (with a pedal and crank dangling from one foot). And alone and without tools, I had a 3-mile walk back to the car.

So easy unclipping, good. Unclipping on either side, good. Not taking better care of bike, bad.