That whooshing sound you are experiencing is the point going completely over your head. The point isn't the injuries. Those would have occurred with or without clipless. Crashing while mountain biking isn't pleasant but it is the nature of the activity. Road biking has nice smooth pavement but mountain bikers deal the hand that was dealt them.

Part of the point (which I'm sure you'll miss) is that I crashed and came out of the pedals without any conscious effort on my part.

The other part of my point (which will be lost on you) is that several times during the ride...including several 20+ mph downhills...my feet didn't slip off the pedals which would have been far more disastrous then the crash that left me with skinned knees.

Still one more part of my point...which I didn't elucidate...is that when climbing a hill at 3 mph in a 16" gear over rocks the size of baby heads, being able to pull up on the pedals...well...make climbing a hill at 3 mph in a 16" gear on a baby head strewn trail possible. You, and others, might think that it would be better to push up that kind of trail but, having walked about 8 miles of the 60 miles because I didn't have the legs or lungs to do otherwise, I can tell you that riding is far better than pushing.