Actually, I wonder if QWERTY is actually better for touchscreens than alternative layouts. In a better layout like Dvorak, the most commonly-used keys are grouped close together, mostly on the home row. This is great for typing because you don't have to move your hands and fingers as much and can reduce wrist strain. But QWERTY does the opposite, moving all the most-used keys to the non-home rows so you have to constantly move between the top and bottom rows. On a computer keyboard, this gives you RSI, but on a small touchscreen, this means the "keys" you're tapping on are generally farther from each other, so perhaps it makes it easier since you rarely tap on two keys that are adjacent.
Amusingly, I switched my phone to colemak. Mainly as I am just happy with the layout. Though, I confess I hate inputting anything on my phone, as I am not a good phone typist. I can almost make the swipe thing work, but I learned how to touch type on a keyboard and it feels very very weird to try and use a phone's keyboard.
