Cartoony style also can mask some of the hardware deficiencies Nintendo has and you can get away with things like low res textures and what not a little easier.
So that probably also is a reason why Nintendo prefers that style.
If Nintendo was still really competing with Sony/MS for the actual core gamer demographic, then this would be a bigger deal (like it was on the GameCube), but since they're really not even in that race at all anymore, if they want to make a Zelda a cartoon that's their perrogative at this point.
They're never going to be the "cool" or "badass" company, so if making Zelda cartoony or even making Link a kid full time is what they want, so be it.
That said do I think Nintendo could genuinely make something amazing if they pushed Zelda to a bit darker/scarier/more realistic. Absolutely. Look at that Majora's Mask video above and tell me that wouldn't be interesting to play in a world of that tone.
