Maybe you're poor at positioning your feet, maybe it's the placebo effect, maybe it's something else. There really doesn't seem to be any scientifically proven benefit, does there?
Racers are sponsored and there's more money in fancy shoes and pedals than firm shoes and rubber blocks, but if you like sugar pills, feel free to keep sucking on Minstrels!
I'm not sure how long I used clips before going back to plain pedals but I never went to clipless cleats because I can't trust my knees and ankles which sometimes lock up anyway.
I think Shimano would pay handsomely for somebody to win the Tour in flats, a marketing win for sure.