There's a long motor-skill learning curve with these. I've tried the "handykey twiddler" years ago and I just could not get motivated to practice enough to use

There's a long motor-skill learning curve with these. I've tried the "handykey twiddler" years ago and I just could not get motivated to practice enough to use the thing in real life. For mobile use, the situation is is even worse because it requires the user to carry another piece of hardware in addition to the phone. Chording keyboards existed well before smartphones came on the scene, and the thinking was that you would have some type of heads-up/eyeglass display like Google-glass. I guess it's just one of those funny things that people thought would be hot in the future but never materialized or turned out to not be desirable when it did.