i think that sometimes the music suffers because of a lack of stage presence. i saw b.b. king live just a few years ago, and he now plays sitting in a chair. the music was alright, but it lacked a certain energy or passion that i was able to catch even off a t.v. recording of one of his earlier concerts.

or, for example, take pink floyd. currently my favourite band, but the reason for their fantastic light shows is because none of them does anything interesting while they play.

my personal feeling is that, if you're going to play live, you should have a good stage act, or else why not just buy the cd?