We aren't in show business are we?
Absolutely we are. As one guitarist put it (George Lynch?), "If it was only about the music, we'd all have our guitars up to our boobies." To that I would add that musicians would sit in tight circle on stage facing each other for eye-contact oblivious to the audience.
There is always an element of showmanship in musical performance. Granted, there is a spectrum with high spectacle on one end (metal concerts with pyrotechnics) and little spectacle (jazz concerts) on the other, but nothing that really counts as zero spectacle. Even a jazz gigger is expected to look the part. Sonny Rollins isn't going to come out in studded leather bracers a la Bruce Dickinson, but he is going to make choices that, however much he is minimalizing the look, acknowledge the standard to look the part.
I don't think one can really dichotomize listening and seeing. They form a set along with the other senses--the smell of a smokey bar, the taste of the libations, etc. all are part of the musical experience even if they form only a small part. Listening to Jaco is great. Seeing Jaco's facial expressions as he plays is even better. This is why I have little sympathy when people cry "no feeling!" whenever they hear something fast and technically complicated. I've been to two Van Halen concerts and whatever you think of that band, what couldn't be denied is that when I saw Eddie play and saw the unrestrained joy on his face I knew I was watching and listening to a guy who would play for nickles--and thus it sounded better.
Now if one wants to argue that a particular gig had too much spectacle to cover up for the bad playing, have at it. I seem to recall Blackie Lawless commenting to his band after being burned after a pyrotechnic accident that "gee, if we played better, maybe this wouldn't have happened."
As far as the expression "I saw x band". That's all it is. An expression. And one that makes sense. If someone said to me, "I heard Bella Fleck a few weeks ago." I'd be inclined to ask, "Yeah, which album?" at which point he'd say, "No, I mean I went to his concert." If he just said, "I saw Bella Fleck." I'd know immediately that he went to a live show.
