One aspect of Sondheim's brilliance was his willingness to let people try new approaches to his work- it seemed like he was willing to sign off on any experiment, just to see if it actually worked. I don't know if it was his conscious goal, but it kept his work alive and even managed to eventually return his flops to relevance (and in the case of Merrily, into an actual hit and bonafide part of the canon). Andrew Lloyd Webber has seemingly come around to this way of thinking, as well.
Your rigid, narrow-minded originalism is the total opposite- demanding that shows be encased in amber and dooming them to be museum pieces.
"...everyone finally shut up, and the audience could enjoy the beginning of the Anatevka Pogram in peace."