I've been riding long enough to have been part of the clips'n'cleats era. Guess what: you can fall over in those too. If anything, you are more likely to fall over with clips'n'cleats, because you need to loosen your toestrap before you can escape. Admittedly, this action quickly becomes second nature, but if you slow to a halt and have a momentary brain-fart, you're going over.

Here's another reason clipless pedals are better: comfort. Honking down on your toestraps will cause your feet to go numb, or hurt, or generally be bad, because you're relying on a 1-cm strap of leather to restrain your foot instead of the whole shoe upper.

Power transfer and more-solid connections don't strike me as valid arguments for clipless pedals. You can be very solidly locked in with clips'n'cleats, which probably explains why they're still relatively popular among trackies. I never saw a set of traditional cleats that allowed for float (although they often acquired a little play just through use),so I think the knee-alignment issue has some validity. I've come to rely on the float in my Bebops.