stage and musical performances are BOTH important and a balance between the two should be aimed.
musical performance should be given vital importance - you dont obsess about it, but cmon, please make it a point to play your instrument right. thats the reason why i hate a lot of these new bands... you call them, emo or something... a lot of them have this "pretend to be angry" posturing and get up onstage spitting and throwing equipment around, while they play songs that have a maximum of 3 chords. i find those bands pretentious and inferior. they are better stage artists than they are musicians. it doesnt take skill to throw equipment around like you are kurt cobain and it doesnt make you unique either. Pete Townshend has been there before.
at the same time, i also hate these really technical bands who are so uptight and hell boring to watch. yes, yes, they play perfectly and their chops are sharp enough to cut a dimensional hole, but cmon, if i want perfect, id buy a recorded version of whatever it is they are playing. they have to at least loosen up and let the audience have fun. these bands are better locked in a studio.
of course, there are excemptions (JAZZ isnt an excemption. ive seen jaco perform, also that priest bassist and man, those guys make me wanna dance), like classical music or opera. they have their versions of stage performances which is very different from rock and pop.
as for eraserheads and pupil being iconic - cmon, pupil is iconic? ... i only went to watch an e-heads show once... and after that i just listened to their songs on the radio. its not really worth it to go and watch 4 guys just standing ... although, i believe if i were to watch them now (if they still existed), id be very busy watching buddy zabala's bass lines rather than their actual performance.
one more thing... it doesnt take big actions and crazy headbanging to have a good stage show. i watched the pearl jam acoustic set on (i think it was '94) ... they were just sitting, but it is one of the best musical performance ive seen. im not a fan of pearl jam, but i really wish i could have seen that show in real life.
its all about honesty and having fun. ironically, that is STAGE PERFORMANCE.