Okay, so you cite PS2/Xbox/GCN era as when the series started being the same thing over and over again. Which is where I'm gonna go ahead and mention that you're wrong.
Super Mario Sunshine: Totally same game, rite? Oh wait, except that it pretty much changed everything outside of the concept of collecting stars
Windwaker: totally the same as always, right? Oh wait, except that it basically revolutionized cel-shaded graphics (something that plenty of games still don't mpull off as well as WindWaker)
Super Mario Galaxy: Oh yeah, this concept has totally been done to death, right? Oh wait, except that it won countless GOTY awards for amazing concepts, mechanics, level design, innovation, etc.
Zelda Phantom Hourglass: We totally have 10 games just like this on the DS, LOL. Oh wait, except that it was the first game to even THINK that something like cel-shading stylistic graphics were possible on the DS hardware, not to mention the first 3D handheld Zelda, not to mention the first Touch Screen Zelda, not to mention the first Online-Play Zelda
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Essentially, the only exception to saying that these franchises are stagnantly continuing the same track would be if you considered Super Mario Galaxy 2 and Zelda: Spirit Tracks the only Zelda/Mario game released in the past 10 years. Because those are the only iterations that took a successful game/engine and did a re-do. Which hardly lasted that long, because now Nintendo are back on track with Zelda: Skyward Sword (which is meant to change the Zelda formula completely, plus 1:1 sword mechanics), and the next Mario edition which will change things up again.