This has more to do, I think, with it being an instrument that is extremely hard to play. It's very difficult to move from note to note, and extremely difficult

This has more to do, I think, with it being an instrument that is extremely hard to play. It's very difficult to move from note to note, and extremely difficult to stay in tune, especially in a setting with large numbers of people around, who, when they move, will change the tuning. Yet it is primarily played by people who see it as a fun toy, or simply don't practice much. For some reason, with the theremin, perhaps because it's an interesting instrument in itself, people find it alright to perform on it while completely unqualified to do so. No one's going to go toy around with a violin for a few weeks and then insist on performing. Or at least, if they do, no one is going to blame the violin for the results. Nonetheless, as some examples, people like Clara Rockmore, Lydia Kavina, and Carolina Eyck all perform very well for technical, difficult pieces, and Randy George does a good job with more modern, popular pieces.