Working with partners or sub-contractors; you are bound to end up working with some very creative people. You have a vision that they need to fulfill; and you probably expect them to figure it out for you so you tell them “just make it happen; do whatever you like”.
When you give someone limitless possibilities, though, they are likely never to find a good one, at least not for you.
By giving even the most creative people just some constraints, you are doing them a favor and you are likely to end up a much happier participant in the interaction.
(via Seth)