"Pessimistic" is a good generalization of the GPL mindset in my opinion: "If I don't make this thing GPL then some greedy-bastard company will make a fortune off of my ideas and never give me a cut, credit, or contribute back." Maybe, but it's a dim way of looking at other people.
And I think GPL actually embodies a really positive mindset. To release GPL code is to believe that there are others out there who will help you without intending to get advantage over you or shut you out.