My personal opinion is that it deals with the patriarchy, and thus the feeling of oppression. Cis views of the binary do seem to involve trans* exploiting, rather than defining, that binary.
A comment I've heard elsewhere in some circles with Jenner being named the "woman of the year" is that it makes many ciswomen feel like men are defined as better women than women.
Not as validation of us, but as oppression of them. And people are so very interested in feeling oppressed.