Hi there GUEST James:I hate to labour a point, but I'm at work so what the hell!
Without delving into the "what is art" can of worms, I can only suggest that if you look at the stuff that Yoko was doing pre-John it was receiving critical attention in art galleries and art circles (which I believe is where they met). This is totally outside of rock n roll notions, and therefore dismissed by many folk who don't get into visual/performing arts.
The bagism stuff they did together caused some stir at the time. "But is it art?!" I hear you shout across the miles. Who knows. Whatever gets you through the night, 'salright! --Callie