Such [insistence on traditional interpretation of Gilbert and Sullivan] would have mattered little had not the D'Oyly Carte enjoyed exclusivity within Britain. After all, "historical" productions of Shakespeare contribute to our appreciation of his plays, as "original instruments" performances of Bach do for his works - but in large part because other performance traditions exist side by side.
This is something people have often questioned me on, as a playwright. I consider it ideal for original plays to be performed as the writer intended, without a radically different interpretation by a director. I always think of that episode of Dream On, where Martin's play, a romantic two-hander about his ex-wife, gets made into an experimental musical without his knowledge (with a greek chorus wearing boxing gloves: ♫ This Marriage is Doomed! It's Dead in the Water! This Marriage is Doooomed! Stick around for the Slaughter! ♫).
But I DO enjoy and entertain new interpretations of Shakespeare or Chekhov because everyone knows (or should know) the original text/story that's being riffed on. Some other writers have achieved such notoriety that I think their work could safely be re-interpreted without damaging the reputation of the artists, though their estates won't allow it- notably Samuel Beckett and Tennessee Williams. The Beckett estate is notorious for only allowing strict interpretations, and the Williams estate recently challenged a production called Blanche Survives Katrina in a FEMA Trailer named Desire, claiming that the one-man show which used Blanche DuBois as a character devalued their property.
Stephen Sondheim in the 80s vetoed a production of Company in which one of the couples was made into a male/male couple without permission, but then in the late 90s granted permission to a college that wanted to cast Marta as a male (so Bobby would have two girlfriends and one boyfriend).
It's a controversial topic; I have frequently directed the original productions of my own plays, just so that I'd be sure of getting my own undiluted vision across to audiences. I can only hope one day I'll be famous enough that people will want to give new interpretations of my plays.
If you want to see your plays performed the way you wrote them, become President.- Václav Havel - Address to the Institute of Contemporary Arts, London quoted in The Independent, London (24 March 1990)