Nintendo's problem I think is that they in effect have a philosophy of appealling to kids/family demographic first and then trying to win over the older gamer after that.
Sony's philosophy is to aim at the 19-year-old, because they believe younger kids want to be that age, and older people also want to go back to that age (care free). MS just basically copies Sony. Though Sega really started pushing in that direction first.
But it's just to get adults to buy into a platform that primarily centers around Disney-esque mascots ... no matter how good the games are. Yes, I know Nintendo love to use the "but adults go watch Pixar movies" ... sure like maybe once every 2 years. How many adults primarily go to watch animated films over live action?