Its so silly that some of them are like "why add this when you coudl improve the UI" its like they don't even comprehend what dwarf fortress is. Toady doesn't care about that stuff he just wants simulationism and is doing what he always has done.
Even
that misses the point.
"Improving the UI" is a big job that really needs other things done before any proper effort (not counting minor tweaks that
might not get undone or made irrelevent as future features arrive). The improvement of the UI does not particularly require the adding of intersex/transexual entities, but also is not required for their adding.
Adding I/T entities was always a job left awaiting tweaks to the inter-entity references in the likes of generated conversation and thoughts (that having no extra UI needs, but internal memory and procgen stacks), plus RAW support for - presumably - cross-caste value inheritances, a likelihood/incidence value (that could be easily set to zero where absolutely not desired!) and various other things that are also not exclusive to this particular implementation. Even if this particular subset of broad changes are the exact prerequisites for this example that had been specifically enquired about.
TL;DR; Toady's doing his thing. The UI is not high enough on his list for some people, and other people are disproportionately invested in the presence/absence of a feature that is an incidental and
partial driver for features that are higher. Drama ensues as (contrived?) outrage meets more eager opinions to which the outrage decides it is opposed.