> All other electronic instruments, with the one exception being the Theramin, have a fundamental problem with human expression. There is an unsolvable disconnect between what the performer's actions and their audience.

Electric bass? Heck, even in synthesizers, you have the EWI or the Haken Continuum.

Guitar (and bass) are obviously and far and away the most successful, but it does a disservice to a number of wonderful inventions to say they're the only ones. Just look at what the Japanese band T-SQUARE does with the EWI to see people innovating at the edges.