There might be an uncanny valley effect involved, in which the play becomes good again if the actors are of superstar quality. I could see this happening if certain "amateur mistakes" are actually required for the play to succeed, and ordinary actors who aren't superstars wouldn't realize this.

I loved the version my local high school put on, but when my local community theater - which does hire professional actors - put it on, they played everything far too straight and it stopped being funny. I've never seen the movie, though, but my father reported the same experience as I did; he also loved Arsenic and Old Lace when his high school put it on, but he never cared for the movie very much.