Bundling COD5 or Fatal Frame or even Sonic would really hurt Wii sales.
It would overshoot a lot of customers. They don't want customers to feel that COD5 is what Wii is all about, because most people already feel like they can't play those games. Overshooting customers doesn't just mean too high a price.
"If it ain't broke, don't fix it" DOES apply here. It wasn't Nintendo resting on their laurels that caused the NES to GC transition. Nintendo altered their strategy for SNES, opting to fight tooth and nail with Sega over existing customers instead of making the non-customer king and removing barriers for them. Sony also altered their strategy between PS1 and PSP/PS3.
If you were paying attention, you would see that Nintendo is not just rehashing any one expanded market title until it becomes a "red ocean" market. They are continually shaking things up, with Brain Age, then Nintendogs, then Wii Sports, then Wii Fit, etc. As long as they keep doing that, they're safe.
And you would also see that when Nintendo talks about the core audience, they mention games like Mario Baseball. They are talking about courting the entire old existing audience, not just one niche of it that likes gritty, M-rated games.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.
