WAV: Re the use of Indian harmonium: I think it tends to be used more in popular and devotional music, and chords are used. In what is wrongly called Indian classical music, the melody/improvisation is, as you say, one note at a time; however, this is always accompanied by drones on the tanpura. A drone is a basic harmony, which has been used in European - including English - folk music for many centuries. It gives a fuller sound, and adds atmosphere, and, as has been suggested, can be easily rigged up on keyboards. It's not un-traditional - far from it. You seem to be worryingly entrenched in your anti-harmony views. Why not try a drone or two in the privacy of your own home, where nobody will know you're at it? You never know....
John Kelly.