If the small keyboard was better for everyone then presumably we would already have them. But my guess is that a keyboard that's too small is just as bad as a keyboard that's too large, so the current size is a compromise based on the average hand size of pianists in the 19th century.

That's why they want 3 sizes. Humans haven't changed -that- much since then, just a bit taller and no doubt on average a little bit more finger reach. This will help solve that issue. I think it's a good thing.

Actually, a large-handed composers' large hands will stop them from using small keyboards. Their wider fingers causing unintentional adjacent note triggering, frustrating them as composers, and losing them competitions as players.

I used to play the harpsichord, whose keys are about 3-5 mm narrower than piano keys. I have huge hands with big fingers, so it was a challenge at first, but after a week it felt normal. I doubt that smaller piano keys will be much different.

I don't think this matters much for competition though? The existing classical repertoire will still be playable by a much larger percentage of women, bringing them into greater parity. Just let everyone use whatever size piano they want and it'll be an equalizing force, just like how reducing the height of the basket would be an equalizing force for height in dunk competitions.

Maybe...

But at least competitively, this is probably self leveling. Large handed composers they play big chords on a small piano, but they'll probably struggle to play "regular" music on this undersized piano.

There's only a problem if everyone has to use the same piano. If everyone can choose their own size piano then hand size isn't a factor

Is that a problem? I thought piano competitions would be about piano-playing skill, not physical hand dimensions.

In the same way that basketball competitions are about basketball skill, not height.