Totally in agreement with you. There are only a small handful of icons I'd be likely to insist on getting credit for. This is one of them because the photomanip it's based on is one I constructed out of several dozen different images until it looked realistic, and the work I put into it was pretty intensive. When all I did was crop and resize an image, I'm totally fine with credit being at the discretion of the taker, because hey, it's not like I took the picture in the first place. The only point credit has then is to let people who like my iconning style know where they can get more.