I think it's pretty simple: America is musically conservative, and when it comes to the mass market, it has to have vocals, and it has to have chord changes.
Listening to and enjoying techno involves a different kind of listening than pop music. A case in point, my brother, who doesn't listen to techno, patiently sat (!) through one of my DJ sets, and then said 'it all sounded the same to me.' To say that techno is a musical cul de sac, that it is confined to a narrow spectrum of sound, is to ignore the techno that is adventurous and branches out from the primal oontz oontz. There's plenty of boring techno. My experience is that certain audiences demand it -- e,g, a lot of european club crowds. But it's unfair to judge a musical genre by its most pedestrian examples.
