How about this, if you don't fall for one reason or another are you biking hard enough?

I've fallen a few times. Once, someone cut me off and instead of crashing into them I took a dive, had i had clipless maybe it would have turned out different. Second time, same ride, after the first fall I cleaned myself up rode 50 miles came to a stop to end the ride and didn't have the strength to unclip, i had sprained my ankle and twisted my knee from the original fall so I couldn't twist out of the clips. Third time, i was cranking away came up on a steep incline on a narrow path, a newbie was in front of me taking up the path struggling to get up the hill so I had to brake hard and didn't have time to shift into a granny gear, I couldn't turn the pedals, couldn't unclip, and I fell.

But back to the topic, I know some people that just didn't have the strength or weight to clip in. They bought a different style and the problem was solved.