I agree with you to a point, but would maintain that a significant amount of behavioural and cultural data coming from the "5 button" research, would also apply to touchscreen devices.
I have enough computers around me to not need a smartphone. The single feature I need from smartphone is tethering.
I am dreaming of cheap 5 button nokia phone (like my current phone) that would provide tethering so that I can use my cheap wifi android tablet anywhere. My 5 button nokia phone looks prehistoric, but it works perfectly and has fantastic autonomy.
My cheap Japanese phone can tether -- but the carrier makes a distinction between packets originating from the phone and those from the computer, and they charge extra through the nose for PC packets (100$+ per month if you exceed a few megabytes, in extra to normal phone charges). All this while I can get a dual-mode WiMAX/3G WiFi router that fits in a pocket, has a day of battery life, unlimited data and transfers much faster for 50$/month. The problem isn't the hardware, it's the carriers.
>The single feature I need from smartphone is tethering. I am dreaming of cheap 5 button nokia phone (like my current phone) that would provide tethering
OK, but the reason tethering is hard is that carriers want to charge extra for it, not because of any decision of Nokia (or any other phone manufacturer)