

BlackBerry, for those that are unaware, allowed one to type super fast and accurate without even looking at the screen. In fact some user interface elements like the old click wheel let one navigate the device without looking at it.
Insanely good battery life that lasted days, lightning fast communication. When they added cameras, they didn’t skimp there either, for the tech of the time.
BBOS could be up for literally months without having to reboot. It. Just. Worked.
As for those that watch video, tiny phone screens of any size are not the best for video. The keyboard phones at least have a place to hold the device, unlike the borderless boring hard to hold rectangle phones of today.


The tl;dr is: Control. Vendors want it, making it easy to run open software would make that control harder to keep.