I think that even though women do crave novelty (whether within monogamy or outside of it) that the cultural narrative is still very strongly for monogamous marriage as the gold standard of what women "should" want and need. It is still overwhelmingly a patriarchal society and open marriages/relationships make up just a small fraction. I think that a lot of women still plug into what they think they are supposed to do/want and never really ask themselves if what they actually want is different. James and I were married for 20+ years before it dawned on me to ask for something different.
It would be interesting to really ask those lesbians more about where they are coming from, but it sounds like the ones that Jim has encountered are so adament that he is advocating for something amoral even if it's consensual, that it seems unlikely they would have the self-awareness to notice what was really behind that.
Still, it's an interesting question.