[dithering]

If your purpose is to allow the device to be used when it doesn't have your full attention - like a car radio, for example - I don't think that's a good solution.

I have a phone with a knurled power button, and a smooth flashlight button next to it. It's a minor example, but dynamically remapping those buttons would destroy a lot of their utility for me.

[Yetanfou]

That is false analogy as you're opposing fixed-function devices - lamp and power - to a device which in principle has an unlimited number of functions. Even if it could also contains an unlimited number of buttons this would still not make it usable in situations where the user has to divide his attention between the device and some other task of higher importance like flying the aircraft and keeping sight of the opponent. That is just why they came up with this interface since it combines the advantages of haptic memory - button three on the left side does this in that situation - with unlimited functionality. All that it takes is a sure way to get the device in 'that situation' and a modicum of experience. A touch screen will never have this possibility as the user always needs to look at the screen to guide the digit to the target - unless the whole screen is turned into a single button of course.

Buttons on the side of the screen are not the correct user interface for all activities, as an example they would be inconvenient for browsing the web [1] and useless to sign for delivery of a parcel.

[1] ...but not impossible: number the links on the screen as if they are footnotes, number the buttons on the side, click the button which lies next to the desired number. If there are more links than there are buttons the last button can be used to select the next set of numbers. If there are zillions of links the last two buttons can be used to page through sets of numbers. Inconvenient, maybe, but it would work.