[nullc]

Doesn't that approach have the downside risk strongly elevating gender to be essential to activities where it really has no business?

I have no idea what your gender is and I don't think our interaction would be improved by forcing you-- by either rule or convention-- to specify something. Doing so would unnecessarily prime my sterotypes and perhaps leave you and/or me worrying that my response was unduly biased by the knoweldge. An effective requirement-to-specify implicitly makes a strong assumption that your gender can be described categorically rather than as, say, the fractal attractor of a complex collection of partial differential equations. :)

For a long time online I've tended to fill out apparently pointless gender fields with a "none of your business". I'm happy to support people identifying in whatever way they find most enabling, but at the same time it feels like a step back to elevate gender as important in contexts where it isn't after working so long to push towards a more gender blind world.