A car has had largely the same shape since its creation, indeed since antiquity.
Sometimes, a problem space is explored to most humans' needs, and no more innovation is needed.
(edit: this said, I'm hopeful there is something new, and people like Bret Victor may show the way with things like https://dynamicland.org/ )
This is not historical reasons, this is just that moving my hands from the keyboard to the mouse is inefficient and technically unnecessary. I prefer mouse only on niche (for me) tasks like screenshot cropping or something.
I am about to test out Niri on my laptop and I expect to be quite pleased with the change.