Michael,
I see your point about this program playing to the 'lowest common denominator', however, I don't think it necessarily, 'can't help but dilute, even corrupt, any art'. I agree that can do that - but I think it can also introduce people to a form or type or genre of music that they might not otherwise be aware of. An introduction to something 'new' (read - unfamiliar), done in a common or fairly familiar format can often be a lead into exploration of the 'new' territory. It would be great to have a 'Celtic Women' performance of traditional music, sung in Gaelic, with on amplification, fancy staging/lighting, etc., and no regard to how 'photogenic' the performers may be, but I do think that the program, as presented, does have a valid place. It would have been nice if their program breaks could have included discussions on the origins of the music, instruments, original language, interpretations and translation process - but that's probably too 'in depth' for pledge week!
Cheers
PB