I always took it as a positive. I read into it that the sooner you deal with the reality of the situation (rather than complaining about it) the sooner you can get about dealing with that reality. This, of course, doesn't apply in situations that are blatantly unjust.
Let's say I get in the car to go to work and I'm running late AND need to stop for gas. I can a) complain about it and drive like a maniac trying to make up late and gas pump time or b) realize that "it is what it is" and that you're going to be a few minutes late. Call work. Get gas. Go on with your day.
I once had a woman dump me by telling me she banged someone else and "it is what it is." It was pretty cold.
