iPad user and many Android tablet users do not have the input devices to hand.
More like, iPad and Android users aren't required to have a keyboard for their tablets to be useful.
As a surface user I would use the keyboard in almost every single case except where I literally was unable to place the device anywhere, including my lap.
Same here. Now I have either a crap tablet that requires a keyboard, or a crap laptop with a poor keyboard and that I can't balance on my lap