I agree that you often see something like a retracted foreskin, uncircumcised, penis in a lot of people's drawing styles. But I see a good amount of foreskin on drawn penises too. However, it's so much rarer to see circumcised men in drawings at all. There's really just a handful of artists that draw it at all and then those that do, do so more selectively and less often than uncircumcised ones. Which I'm fine with and it makes sense to do it that way honestly. A majority of drawn male porn is of characters and series originating from Japan. It would be weird if people drew Japanese characters as circumcised often. On the other hand, some American comic book characters might make sense to be drawn circumcised.