> But whenever someone answered the call and built a Smartphone with QWERTY keyboard, the product failed commercially, simply because also to people claiming they want such a phone, at the point of sale they were less attractive than their slimmer, lighter, all-screen counterparts.
No. They were a) rare and b) much more expensive.
AFAIK only Blackberry had a phone with QWERTY keyboard.
Buttons are much more expensive than a touchscreen (see cars for examples).