I think there's some confusion among terms.  To have [i]ideas [/i]limited by setting, plot etc. doesn't necessarily mean that [i]creativity [/i]is limited.  Also, do you equate creativity with ingenuity?  When faced with a creative framework, an artist has to work harder to accomplish her goals.  Does the situation therefore limit or encourage creativity?  Or are limitations and lack of limitations two different kinds of stimuli that both engender creativity in different ways?