> Touchscreens on mobile works because it's cheaper to build than a number pad, and way cheaper than a keyboard, it's cheaper to extend the touch screen so they don't use any real buttons on the front of most androids. The flexibility is helpful for text input.
Consumers didn't flock to a more expensive phone (the iPhone in 2007) because it was cheaper to make (it wasn't). They did so because the touchscreen enabled new forms of interaction not yet possible, enabling full-screen games, photo viewing/shooting, and web browsing to name a few.
It was cheaper to make the iPhone with a touch screen, than it would have been to make it with a slide out keyboard. While the iPhone has a big market share in the US and a few other high income countries, touchscreen phones have taken over in almost all markets, even inexpensive phones, because they're cheaper to make, if you've already got a large enough screen and a fast enough processor in the phone for other reasons. You can still make a cost constrained phone where buttons is a better choice, but a cost constrained android isn't that much more expensive in absolute dollars, and provides so much more functionality so it only makes sense for the most cost constrained buyers, or those who eschew a smartphone for other reasons.
Consumers didn't flock to a more expensive phone (the iPhone in 2007) because it was cheaper to make (it wasn't). They did so because the touchscreen enabled new forms of interaction not yet possible, enabling full-screen games, photo viewing/shooting, and web browsing to name a few.