Because everyone has their own favorite way of doing things. Just because you like touchscreens doesn't mean everyone should like touchscreens.

I personally prefer a non-touchscreen. I don't care about fingerprints because they don't show up that much on an eInk, but I don't like the fact that the touch UIs I've seen for eInks are always sluggish due to the nature of eInks being slow to refresh. It makes me feel like I've got a touchscreen attached to an old PC running the 8086 Intel processor! I also don't like having to avoid touching the screen. Often when I set my reader down for a few moments or pick it up again I manage to accidentally touch the screen. With a touchscreen reader this will page back or forward depending on where I touched it. If I hold my touch it might page 10 or more pages. Now I'm stuck with looking for my place in the book. Also a touchscreen can page if clothing or other objects come in contact with it. I've got two cats and they are known to cause many inadvertent page forwards or backwards with their tails alone. And most importantly, I much prefer paging with buttons rather than touching/swiping the screen.