I think we are evolved to live barefoot, that our biological systems are designed through the process of natural selection to provide our feet with protection from the "risks," that callouses develop as a key element of those systems, and that this "doctor's" ignorance is indicative of a much bigger problem in our society -- that doctors do not become doctors anymore by learning the intricate workings of the body, but instead are trained to serve specific functions in the economy, regurgitating BS they actually know little about, but are trained to memorize and repeat, for profit; they are essentially overpaid drug pushers.
Additionally, Nature is Supreme and humans are delusional to think their own inventions are somehow superior to natural selection. Shoes cause substantial problems for the feet, which in turn causes other problems for the body/mind. Shod societies are afflicted with substantially higher rates of violence and crime than barefoot societies. Maybe there's a correlation.
We need to stop living in virtual reality and reconnect with Nature, in general, as a species.