The question should be, why in the hell does Nintendo have to create new characters when the ones they have had from the 1980s sell in the tens of million no matter which gen they appear in?
The obvious counter argument is, with Sony and Microsoft creating new IPs such as Halo, God of War, Gears of War, Uncharted, Viva Pinata, and on, Nintendo is losing the young gamers because they are growing up on what their big brother is playing. Since little brothers look up to big brothers as a role model, they will gain some of the biases their older brothers have against other games.
Problem is, older brothers like me grew up on Nintendo games. We may be playing more mature games now, but that does not mean there is no nostalgia.
Nostalgia is underrated, Nintendo knows this and this is why they drop a core game once to twice a generation. They understand that if you go the Tony Hawk route with franchises, then in a couple of generations the game will have had so many bad sequels and crossovers, any sense of nostalgia is equally weighted against a craptastic game like Green Day: Rock Band, Call of Duty: World at War, any game with LEGO in it, and on.
Nowadays, publishers have such a short-term, quarter by quarter outlook they lose sight of what made a franchise great and sacrifice it on the 2K"fill in the year" altar because they need to meet their internal expectations. You see this right now with Call of Duty and Assassin's Creed. Both had games in 2009, released a new game in 2010, and will release another in 2011.
It is only a matter of time before annual releasing of Call of Duty and Assassin's Creed milks the franchise out of any nostalgia milk. Once the nostalgia is gone, a new franchise will replace it and the cycle of killing a great game will continue.
