I think that's because, even hardcore smartphone with physical keyboard users have accustomed to touch screen, it's just few outliers and security conscious people are using the setup being discussed here.

That said, I see a resurgence of smartphones with physical keyboards and once people get used to them, they may seek better screen/keyboard/performance with a pocketable laptop but the GSM integration is a major limiter for many. It's not like people are going to throw away their smartphones for a portable computer anytime soon.