They also, unfortunately, ran into hardware issues. They were exploring the novel battery form-factor and storage space when lithium chemistry was even less understood than it is now; they had a sequence of models with batteries that went EOL too quickly, enough to (at best) make them seen as unreliable in the consumer space and (at worst) seen as trying to put people on an upgrade treadmill (back when that was a bad thing, before people understood that would actually be Apple's whole model with iPhones).