Amber walks around actually barefoot most of the time as her gypsy Yasme. I know someone else who wears flip-flop type sandals as an Asian based elf. If Zehnyu had been intro'ed when Vibrams were available, Ali probably would have rocked them. John Quigley as Parduc, a black panther sarr since permed, was in all black all the time as "just fur" and Vibrams would have worked just as well. Bill Hawkins as an NPC big-bad sarr wore grey Vbrams that matched his costuming color and no one even mentioned it. I was planning on getting a pair for my forthcoming high Orc, because of the pain that most structured boots cause my feet.
I know many, many kin and savage races that matched shoe color to costume color to be "barefoot." What's the difference between wearing brown Merrill's slip-on boots and wearing brown Vibrams, if you're a brown sarr or kin? The continuity you're talking about is entirely OOG, because its something you're not used to seeing as a certain thing (seeing black underarmor as dark elf skin, for example.)
This seems really similar to the discussion that was had when the most recent edition of the rulebook came out and in a picture someone's Transitions lenses were tinted because of the glaring sunlight. No, sunglasses aren't and never should be an acceptable thing, but the player needed to wear his glasses and not need to buy new ones. Some people got all up in arms about it, some people went "whatever, they're his OOG glasses." This is a YOMV (your opinion may vary) issue, and shouldn't need to be codified on a national level.