The BBC is currently asking (in their usual rhetorical way) Why do we all use Qwerty keyboards?
There are many reasons. The development of it in the first place is there for a lot of reasons, but ever since it’s largely been inertia that’s been keeping it in place. The barriers to entry for any new keyboard design are massive, purely because of the amount of time people have spent learning to live with the layout and because of the number of keyboards out there.
But the biggest reason is because the only real widespread alternative that I’ve seen is the AZERTY. And it’s French. Do I need to say anything more?