My theory is that in trail races we often have to ford streams or slog through mud puddles, thus having the mental experience of running with wet feet is good. Moreover, there's the actual physics of it, the hydraulics and friction and skin dynamics of running with wet feet. I think there's much value in toughening one's feet.
So in yesterday's 10 miler I passed up an opportunity to use this perfectly good bridge over the Conococheague Creek...
...in favor of this:
I know I've blogged about this before, but even in the winter the water is largely out of your shoes within a mile or so, and within 2-3 miles, it's hard to know you even had your feet wet. So, running with wet feet is not big deal. Figure, in August when it's 90 F, your feet are pretty darn wet in your shoes anyway just from sweat, so there's not much difference.
The one lasting effect yesterday when I got home (some 4 miles after the crossing) was frozen shoelaces. Made it a bit tough to get my shoes off.