And Mark Rosewater of Magic the Gathering design. "Restrictions breed creativity" has become a catchphrase associated with him.

If an author is told to write a science fiction story, that gives no hint or help on what to do with the request. Tell him to write a story about tigers escaping during the process of Mars terraforming, and now you've got something.

In Magic terms, being directed to design a creature doesn't push the designer in any useful direction. But "Design a small black creature that uses this set's new mechanic", and it will come to be. Much of MTG is conceptualized in such ways, right down to the color pie, where what colors can't do is even more important than what they can.