I'll pile on... I have 6 bikes (all are used to commute) and only the Globe Daily (city bike) has platforms without retention, and that's because I ride this bike with street shoes. Every other bike has one version or another of foot retention. This has been true for my bikes going back to the late '80s.

My story about (lack of) foot retention - a few years back, when I started winter commuting, my winter bike had platforms without straps. I was on a climb, coasted for a second as I was check cross traffic, when I started pedaling again, I stood on the pedals. The free hub had froze while I coasted, my pedals free-spun, my food slipped off, hit the ground and it was everything I could do to avoid a wreck. Painful, awkward, and scary. I've had the hub freeze since adding straps , still not fun, but MUCH easier to control the bike until you get the free hub to re-engage or come to a stop (& swear about the frozen hub).

With foot-retention, I have never had a fall at speed. The only falls I've taken are at a stop or near stop, simply tip over. Embarrassing, but not much else.