I noticed in an earlier comment that "platform pedals only allow downward force on the pedals" and this is simply not true if you use BMX style pin pedals and a softer outer soled shoe you can effectively push down, forwards and the proverbial 'dog poo' swipe backwards. Pulling the opposing leg on the upstroke is easy and your legs can be trained to not come off the pedal. That small area in your pedal stroke (contrary to popular belief) does not provide much of a power increase during normal pedaling at normal rpm.
Pulling up can be helpful in rare circumstances but it takes a conscious effort. When racing, solid attachment to the pedals has its place such as, pack riding in the rain and balls out sprinting but most of us commuters need the flexibility of being able to stop and go easily and walk around too. I've spun a 65 inch gear up to around 25 mph with no attachment and while I don't know my pedal cadence, I'm sure it was quite high and my feet did not come off the pedals. Were it a race though, I would not trust my feet to stay on but I do not race and I seriously doubt many actually do. Most of us merely fantasize about racing and I suspect most racers would not spend much time taking about pedaling dynamics, regardless.