1) The whole show's essence/idea is that it's a tiny, shoestring spoof of big Warner musicals. Putting it on Broadway, no matter how cheaply produced, shows that no one at the helm understood the show at all.
2) Except for Lesli Margherita, the cast was, at best, merely adequate. Eloise Kropp, although an excellent tapper, has no star quality, an uninteresting voice, and only basic acting skills. If you're putting up someone to compete with the memory of young Bernadette Peters in a star-making role, you need to do better.
3) Randy Skinner has a great eye for old-fashioned tap routines, but as a director (or choreographer of any other kind of dance), he has no surprises to offer.
Isn't that enough to do in a show?