Whoa there Mr stock, the mental aspect is important; its my conjecture, that the "performance" in the genghis tron OP clip is very much ABOUT therapy for the singer, the band.
How one could like that stuff, im not sure; you might notice, in that clip, the extent to which the handfull of audience was "getting into it", not much it seems.
I could tell you about a band, in a country town, doing the usual thing, went for a stage dive, and nobody knew what to do, the lead singer just went *splat* on the floor, people just milling around, "what the f**k was that?"
They may have heard of stagediving, but didnt beleive it, or know what to do. Maybe they just thought the band sucked, and collectively thought "hey, lets just NOT catch him", who knows.
Music is very personal, that's all there is too it.
As for enrico caruso, he may have been the best of his generation, or era , but even he was stuck with old material, a stifling tradition of opera.
Or, was the tradition the only thing that held its popularity?
Why are "greatest hits" of the 70's etc, still in existence, if not a vast personal requirement of the music itself, to reflect, somehow, on a persons life , familiarity, identification, or "tradition"?
Possibly too deep, i dont know.