I would MUCH rather buy and use a cheap external keyboard that can be trivially disassembled to clean. Plus then you get to sit back further, and not look down at the screen as much. Win/win as far as I can tell.
FWIW, you can also see them used for switching to DVORAK and other alternative layouts.
And for adding a second writing script to a keyboard with Latin-only labels.
Put another way: I am absolutely certain that more users would get a Mac with a Dvorak layout by mistake and want to return it than would actually purchase and keep one.
Plus Apple already does this for 20(+?) languages, some of which have difference shapes, which for a macbook means different frame milling. One more letter arrangement isn't much.
Plus we're overestimating the number of users of alternative keyboard users in the world. There's maybe a few hundred thousands of us. Compared to the millions of speakers these 20+ languages have.