Most, or at least some, of my bikes have no dust caps on the cranks. Oh, I have a few DC's sitting in my stack of small parts, just never saw the need to put them on.

A few years ago when I'd just finished building the Masi I happened to stop at The Bike Stop, a small but nice shop with a door open to the Minuteman Bikeway. The proprietor was a vintage bike entusiast so he went nuts over the Masi (which I enjoyed). Then he started talking about all the bikes he and friends had collected, not just certain models but actual bikes ridden in various races through the years. Anyway he told one story of a friend who had searched for ages to find the correct dust caps of a particular bike. After finding them he happened to show the bike to some ex-pro racer or coach or something, and was promptly told that the first thing you did on a bike to be raced was to take them off and throw them away. If you had to do any crank or BB work it costs time to take the dust caps off, time you couldn't afford. Of course those of you closer to racing than I ever was probably knew this already.