I broadly agree but I do think there would be a place for experiencing concerts as they were when the music was written - not as the norm but as some sort of HIP experience.Regarding making concert halls more informal and relaxed, I think it's worth mentioning that Boulez himself also organised his so-called Rug concerts in Philharmonia:
"Pierre Boulez, the avant-garde French composer & conductor, removed every seat from the orchestra & filled the space with red rugs & foam-rubber cushions The new decor is designed to encourage concertgoers to lean back or lie down & listen to the music in a relaxed frame of mind. Boulez commented, "There is so much formality involved in the performance of music that we make it hard for audiences to get emotionally involved." Philharmonic Hall was crowded with people of all ages. The orchestra was not on stage, & it was possible to watch the conductor from behind the orchestra. The acoustics were much improved: by moving the orchestra, Boulez created a better sound mixture in the Hall. Weber, Brahms, Ives, & Stravinsky selections were played."
I personally think that this is a pretty genius way to introduce people to a wide range of different repertoire - exposing them to composers other than Mozart, Bach, and Beethoven. I think this is important because there are people who might be a lot more hooked by modernists or contemporary avant-gardists, and making it more informal removes the "highbrow" tinge that classical music otherwise might carry.
However, I don't think that bringing classical music closer to entertainment by allowing people to actually talk and make noise is necessarily what I think is beneficial - there was a reason why this "tradition" was discontinued. I suppose any artist wishes to be respected - Wagner famously caused a huge scandal by putting the ballet section into the beginning of Tannhäuser so that anyone who was late (there was a rich, aristocratic French gentlemen's club who had made dinner plans that would have caused them to be late) would have not been able to see it. That was also the reason why Bayreuth was built the way it was. Talking in a cinema is not accepted either, although it carries a great value as an entertainment - I don't think that being able to socialise during a performance is quite ideal. So, for the time being, I personally prefer how Boulez made concerts more informal while still fully respecting all the artists involved. But then again I've never been able to experience the OAE concerts which Portamento described above - maybe I'd like them. Who knows .