Toy Store Planning Game Analogy

On the XpMailingList, JohnBrewer described a toy store analogy he uses for the PlanningGame:

Feature negotiation without the planning game is like a kid in a toy store:

Kid: I want the scooter! And the Star Wars Play Set! And Kingdom Hearts!

Parent: I don't think I can get you all that.

Kid: But I waaaaaant it! You'd get it for me if you loved me!

Feature negotiation with the planning game is like a kid in a toy store with an allowance.

Kid: I want the scooter! And the Star Wars Play Set! And Kingdom Hearts!

Parent:

Well, you have $60, so figuring in tax, you can get about $50 worth.

The scooter is $20 and the Star Wars Play Set is $30. But Kingdom Hearts is $50.

Is Kingdom Hearts worth as much to you as the scooter and the play set?

Kid: Hmmm.... Can I have any more money?

Parent: No.

Kid (possibly much later): Ok, the scooter and the play set.