I have a friend whose startup cared was doing a surgical product; after I told him my story he called up a bunch of plastic surgeons and went and observed a bunch of them.
Both of us were interested in workflow; the actual science we had done on animals of course, but our research was aimed at seeing if the product would be viable (could be medically wonderful but if the doctors don't care they won't use it on the patients, even if it improves outcome).
I don't think we could have done this at a hospital, but given that it was surgery (surgeons have a lot of freedom) perhaps we could have.
I had that happen to me, but it wasn't my face where the excision happened, or that was photographed, so it may really be standard procedure. My guess is so that in follow-up examinations it can be determined if any remnants remain and/or spread.
But my incident was about 20 years ago. Today I would be very suspicious, like you are.