Ah, the old movie-to-musical debate.
To me most of the best movies made into musicals have been adaptations and not a scene-for-scene telling of a story we already know. Look at Nine, Sweet Charity, Night Music and the relatively recent Full Monty.
There is a basic question when adapting any property. "Can we tell the same story better?" Prime example is Big. Not a bad show at all, but it gave me the exact same story as the movie with some nice but not terribly memorable songs added, and I could have bought the movie for 20 bucks anywhere.
The Producers is an exception to that rule, but after Lane and Broderick left, maybe some seams began to show in the script.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher