If we are talking about sociology journals, then yes, I agree, cis is the right term. If we are talking about general use, like in newspaper, then there is natural reaction of bewilderment - why would you need this term? Please understand that most of the people (me including) do not meet/do not see trans people in their lives (at least they do not know they are trans). I personally know exactly zero of such people. So, the world from the point of not-trans person looks very different - they read about trans people on internet and in the news, it is rare phenomenon, that is not even observed by them personally. That’s why it seems as really unnecessary world. Do you have a special word for non-albinos or for non-red-heads? And those (albinos and red-heads) they see in their life more frequently.

And here is where insisting and pushing this word on other people comes at disadvantage to trans community - the right will use any opportunity to use bewilderment of non-trans people to propagate whatever stereotypes they want to propagate about trans. They will say that trans people are “forcing” other people to call themselves “cis”, and that this is derogative term, and nobody likes to be forced to do something like that.