I suspect I’m not really understanding your questions, here, because the answers seem really obviously self-evident. The terms are needed when you want to distinguish between one group of women (those who were born with a disconnect between their physical gender and their mental gender) and a different group of women (those who were NOT born with a disconnect between their physical gender and their mental gender). And “cisgender” is a lot easier than typing out “women who were not born with a disconnect between their physical gender and their mental gender.”
I’m not seeing how the two terms make anything “more difficult” for anyone. On the contrary, once I learned the term “cisgender,” it became vastly easier to write about trans issues with tying myself in knots avoiding loaded language like “normal” or “natural” or (god forbid) “real” women. What about it makes you think it’s making things more difficult?