It costs man-hours. A game like Skate. will never have the budget (wwhich in turn means less staff, less time to complete/polish, less absolutely everything) of a game like GTA. Deadlines are for revenue. Shareholders want them to meet expectations and the quarterly guidance might have certain game releases baked in...also, putting it off a year means your total earnings for the year would be lower by whatever that game would bring if it were released on schedule..