[JohnBooty]

    I agree constraints can generate creativity, but 
    is there evidence that constraints generate more of it?

It's hard to talk about evidence for something as subjective as creativity, right?

I think the strong general consensus is that the right kind of constraints can indeed foster innovation - think of the constraints imposed by, say, early video game consoles. Or forms of music that grew from various constraints - the energetic DIY ethos of punk, or how hiphop thrived within the constraints of working with turntables and early electronic tool vs. live instruments.

Of course, the kinds of constraints matter. I think you're talking about societal constraints. I would guess that they generally have a much more negative effect on creativity.