Absolutely, I can't even think about using mine barefoot. I like to hang completely vertical and that puts some major hurt on the ankles. I've seen foot holders that look like they do a better job of evenly distributing the weight on the ankles. But even then I'm guessing shoes would be better.
I won't touch your last sentance, though I'm not sure I agree necessarily. I had a fun girlfriend in the day that enjoyed getting romantic in nothing but her high heels - sorry.