I think a big part of the issue is people who don't know the varieties and genres of cuck style porn. There are many people like you've mentioned who play with others without jealousy, but I think many of them would go with the label hotwife/hothusband or stag/vixen or even just swingers.
The humiliation, jealousy, and racist aspects are mostly tied to specific types that call themselves specifically cuck porn instead of some other variant, and that's I think what most people are associating with it.