The big downside remaining would be that you’d have to get used to hovering your fingers over the keyboard and having even the slightest touch count as a press.
That’s a pretty big downside, and, in my opinion, the reason that touch keyboards haven’t really taken off for any kind of “long-form” writing. Even for devices that are ostensibly mostly oriented around touch UIs, such as smartphones and tablets, there is a large ecosystem of physical keyboard accessories which allow the user to rest their hands on keys and provide greater feedback for key presses than a mat.
That’s a pretty big downside, and, in my opinion, the reason that touch keyboards haven’t really taken off for any kind of “long-form” writing. Even for devices that are ostensibly mostly oriented around touch UIs, such as smartphones and tablets, there is a large ecosystem of physical keyboard accessories which allow the user to rest their hands on keys and provide greater feedback for key presses than a mat.