You do realize the previous record holder was Twilight Princess, directed by Aonuma? And this transition towards more puzzle elements and a less open world design predated his time. Ocarina of Time was the template for every Zelda that came after. Changes to the formula made to facilitate the transition to 3D during an era of extremely limited 3D hardware are the foundations of the 3D Zelda formula from OoT to SS. Not Aonuma's insidious influence.
Also, you are aware that Zelda as a series was a 4 to 7 mil series more or less from day one. The decline you speak of was not much of one. Wind Waker out sold Majora's Mask and near matched Link to the Past, for example.
Also the whole "going back to its roots thing" is an interesting perspective but there's far, FAR more to it than that, design wise. And the heavy puzzle element is still there but in a very different way.
Also, all that aside, even if we go with your "Zelda needed to be fixed!" mantra and give credit nearly entirely to this "return to its roots" explanation, this is still incredibly shocking. The original Zelda couldn't even outsell Super Mario Bros 2, much less Super Mario Bros 1 or 3. And no other Zelda came close to matching contemporaneous Mario games either. For Zelda to beat the best selling 3D Mario game of all time and blow past 15 mil, more than doubling the sales of previous top sellers in the series, is an incredible leap. The Zelda brand is far stronger than it has ever been, far eclipsing Twilight Princess, Ocarina of Time, or even the original Legend of Zelda. There's no comparison.
So no, can't agree with much of anything you posted as it is mostly demonstrably inaccurate or oversimplified.
Yup. I agree with all of this. Well put.