That's because you don't ride fast or hard enough. If you had to travel at race pace, 25mph or so with occasional bursts at 35 plus, jump hard out of corners and go from cruising up a climb to powering flat out in an instant you'd find that flats were both useless and dangerous. That's why you never see a racing cyclist without their feet secured at any level, not everything is just about fashion.
Now if you prefer flat pedals for your type of riding, fair enough. But implying that clipless pedals or toe clips and straps have no benefits is just rubbish.
This is very true. You simply can't maintain high power, on variable terrain, without bindings. If your rides are billiard table flat, or big descents on to long flat bits, then sure, flats are fine. Your power will be cack, but your average speeds will flatter you. You need clipless to get a high, consistent power output, and to get a nice quick Cadence acceleration, and maintain that Cadence. The most efficient way of producing big power, being Cadence biasing your pedalling, owing to the fact that it's easier and quicker, to ramp your Cadence up, and maintain it, than it is to ramp the Torque up.