I think that there are plenty of "Western" musicians who study the classical music of North India (which is what I assume is meant by "the Indian instruments), and many other "non-Western" traditions, especially in the many ethnomusicology programs and departments in universities all over the U.S. and Europe. Generally, ethnomusicologists believe that studying a music culture to which one is not native is an important way to learn about that culture. And of course learning about the culture, usually through some sort of "fieldwork" or "cultural immersion" is considered essential to acheiving an understanding of the music.
I think that the problems Richard Bridge brings up arise, not from simply learning or playing "alien" music, but from attempts to represent oneself as something that you are not. For example there are many people who present themselves as bearers of a tradition, like belly dancing or hula or even irish music, yet their knowledge of these traditions is superficial at best and insultingly cliched and stereotypical at worst. I think that Euro-Americans are still trying to sort through the karmic repercussions of blackface minstrelsy, coming to grips with the urge to mimic and claim ownership of that which is seen as exotic. Maybe the issue of power is the important variable here. When someone in a position of economic power or advantage claims ownership of the traditions of a culture that has less power, that's cultural hegemony (BAD). When someone from a position of economic disadvantage claims ownership of the music of the elite or the powerful, that is subversive reappropriation of cultural capital (GOOD).