The real question and problem is that Nintendo isn't evolving their franchises. From the perspective of a guy who played every game in the series, that's an issue. From the perspective of a kid who just got his Wii, he doesn't care. And from the perspective of a loyal fan, he doesn't mind either. But it's not going to be a complete carbon copy, and even when it is, the fans bitch but the game ends up selling anyway (Twilight Princess).
So, from a business standpoint Nintendo is pretty much genius for keeping their franchises so very stagnant over the ages. Zelda especially. The fans don't even want it to change, that's the thing. Sales show that much. Actions are louder than words.
If Zelda is an extreme of that, then I'd say Mario is the exception to the rule, however, because the 3d series flops time and time again and yet Miyamoto keeps on making new ones. When I say "flop", I don't mean they totally tank, but compared to the 2d games they're pretty fuckin terrible. They should at least be given credit for that. Plus it's not like Metroid and Kirby are as bad as the Zelda games are. They change things around pretty frequently.
summary - Bitch about Zelda, but be thankful for Mario.