as a complement to that perspective, i think we're all basically experiential learners, and seeing, hearing, and touching/moving are simply parts of the "experience". sure, one person might focus a little more on the voice of the speaker, and another might be watching more intently, but all of those components combine to create the immersive experience that locks new information into our brains. but as you say, teaching should incorporate mutiple modes of stimuli, because all learners need all of the modes.

incidentally, that's why most conferences and such gatherings are not so useful for learning new things--they're designed so that people talk at you, rather than involve you. the purpose is often to display the superior knowledge/ability of the speaker, for various commercial purposes (having been on both sides of this).