Um. Why precisely should people's gender/sex/sexuality/sexual identity/... be recorded by the government apart from pure statistical exercises like the census?

I agree(*), but I think making that change would require a much larger change in attitudes, and in the mean time there needs to be something to acknowledge that not everyone is m/f. ie I think selectively (and incrementally) removing gender references is going to be easier than removing them all and adding them back as necessary, at least to begin with. But I think the endpoint we want is the same, and once the incremental process was far enough along it probably would be best to do a wholescale de-gendering.

(*)Well, as someone whose job involves using pretty much every sort of government record that exists for demographic analysis (the census is too infrequent, lacks certain information, and doesn't have any information on the ways people's live change over time), modulo issues of practicality and privacy etc I'm in favour of as much relevant information being collected as possible. But not to be used to make decisions about any individual, just to study large scale trends.