Here's what I want, roughly in order of priority:

1. long term OS support
2. repairable
3. privacy friendly
4. small

I currently have a Pixel 8:

1. 7 years software support, maybe more
2. 6/10 on ifixit score; not great, but better than many
3. supports GrapheneOS
4. on the smaller end of "normal" today

A community-supported Linux phone would be awesome, since I'd get 1 and 3 by default and 2 by convention, but they don't meet my minimum needs from a phone: reliable basic feature support. Hopefully we get there by the time my Pixel dies.

I just want Star Wars style comlink. Wearable on my belt or neck, with a strap in case of dropping it.

Will have to be a bit bigger, to have enough keys. And some display, preferably monochrome text-only.

But in general it should be a device not emitting horrible blue light all the time.

About form - I think something round with keys on the sides is still a good idea.

I'm guessing it's because most women carry their phone in a bag, so the bigger phone isn't inconvenient and has the advantage of the bigger screen.
And I suppose most men prefer the bigger screen size, and they are convenient enough in the available sizes. I use a 6.7 inch, and it fits fine in a pocket for me.
Also note that although we have way bigger screens on modern phones, the bezels are way smaller, on the first smartphones the screen was only about 50% of the front face. So a 10 year old 4 inch phone can be about as big as a new 6 inch.

we can't have small phones because the os design can only be so flexible before it starts either being crap at every size or having so many edge cases that internally it's stupid complex.

having limited sizes means the sizes they do have can be well covered

Because people don't buy them.

They suck and also the higher capacity batteries take up too much space now.

There are small phones. There's more small phones than big phones. And I have big thumbs so stop whinging about the minority.

Edit: Omg I just lost to clickbait. FUCK.

Phones are already too small. I use a fold because it's the only way I can get a decent sized phone now!