If you think of the book, Moore and Chamberlain are not bad choices at all. There was nothing off the wall about their casting (and surely they were deemed box office -- and this in the days before TV stars were yanked in routinely to sell tickets). Both actors could sing, and both had a following. You have to feel "if only..." Because had it been good, it might've been very good. It's not exactly a hard-to-picture musical property, and if written in the spirit of the book, not so much like the sentimentalized film, it might've been superb. Of all the "what where they thinking?" shows ... well, no, this one at least started with a sound idea, with stars of the moment that might've made it work, and well.
"I'm a comedian, but in my spare time, things bother me." Garry Shandling