Adding a physical keyboard would have to increase the base price of the edge.
Making the eInk screen touch-capable means adding new, different hardware and likely a higher base price again.

Other than losing the cursor control keys in this last software update, I think the onscreen keyboard works fine. Accuracy is very good. Most others agree.

If you want an external keyboard you can get a nice, inexpensive external usb keyboard. I have a Solidtek mini which is very portable and good enouh for touch typing. When the edge supports bluetooth keyboards this situation will get better.