InCopy users sometimes take too many liberties with their abilities to change copy. Flowing copy is one thing, but shoehorning in more or less copy than intended allows for too much grey area, and it can take more time to go back and fix what they've broken than it would if that ability was limited for them. If InCopy settings in an InDesign document had check boxed that toggle which abilities InCopy users would have (and grey out disallowed settings), that would be wonderful.