Cis annoys me as well as its always used by their community in a derogatory way along with the fact, as you say, woman or man is perfectly adequate to describe someone who identifies with their birth gender. Im actually quite sick of it being pushed. If you choose to be different thats on you. I find it baffling coming from the generation that pushed for gender equality and gender doesnt define you etc that suddenly its so important that people get upset that they arent the other gender.