My rules for barefoot riding are: roads and rails to trails type trails only. Nothing skinnier than 700cX32 w/ at least SOME tread. Group riding ok, but NOBODY next to me. In effect, the rules I impose upon myself for barefoot recreational/fitness/X-training cycling make my cycling safer because of it.
It's like the way I longboard.....falling is not an option (I'll be 60 on my next birthday, have multiple arthritic joints, and have a cervical spine that will turn me into a quad if I crash).
I'm not racing bikes, and riding barefoot makes it more comfortable and enjoyable to me, and probably overall SAFER because of the limitations.
If anyone needs any justifications for anything else they want to do, I'm an EXPERT at stretching the facts. Just let me know what you need justified!