I gave a pair of soaking wet Colorado Trail backpackers a ride down from Kenosha Pass in a heavy downpour once. They couldn't ride in the truck because of my dog and they were dripping wet but I wanted to help them out. I've had to hitchhike when backpacking before too. My wife has ridden back there for the half mile from the CDOT lot down to the front row parking at A-Basin a few times....because she didn't want to get out of bed at 6AM to make the move just to go back to sleep to wait for the lifts to open. I guess it was a really bumpy ride through the snow-pothole lot. :)
Like several others, it is my choice to not do it and certainly not as a standard habit or anything as 9 times out of 10 it can be avoided (or 99 out of 100). But having said that if the situation came up where it was the practical thing to do I wouldn't have a problem doing it on some occasion. Getting some people out of the backcountry for example.