I personally don't take that command as literal. I believe He was speaking of hospitality. In those days (and earlier) it was common to do such a thing for your guests. They had walked to your place, either barefooted or opened shoes/sandals so getting your hot/cold, dirty feet cleaned was a pleasant thing to have done. Today, that's just not applicable, there's little need for it - we drive everywhere, our shoes not only cover our feet, they pad and protect them, and most people either wear socks or stockings. (You gonna stand in someone's living room and remove your pantyhose? I'm not!! lol).
I think that passage is simply an instruction to treat your guests like royalty (in whatever way that would take in what period of time you're living in), serve their needs.