You are right that a lot of features weren't brought to current smartphones, just as current OS are not 'productivity' focused the same way windows is for instance.
I personally think it's because they just weren't worth it for the general public (including pros). Keyboards on android devices didn't convince, interestingly stylus and heavy multitasking are kicking and alive on the Samsung Note series, but only on the iPad for iOS.
'PDA's for specific, dedicated use cases are still a ton in the wild, just as custom android devices also flourish in the manufacture, retail or goods management world (basically "true" productivity-oriented worlds). They found their niche in that respect, the same way Google Glass also went to the business world in face of customer resistance. I see it as a natural evolution in that respect.
I personally think it's because they just weren't worth it for the general public (including pros). Keyboards on android devices didn't convince, interestingly stylus and heavy multitasking are kicking and alive on the Samsung Note series, but only on the iPad for iOS.
'PDA's for specific, dedicated use cases are still a ton in the wild, just as custom android devices also flourish in the manufacture, retail or goods management world (basically "true" productivity-oriented worlds). They found their niche in that respect, the same way Google Glass also went to the business world in face of customer resistance. I see it as a natural evolution in that respect.