Why couldn't we have the ability to make our own stories and make our own uniquely crafted dungeon designs and world to share with everyone?  I think a Zelda maker would have MASSIVE potential and would be completely different than your typical RPG maker or Mario Maker.

I guess if they make the tools complex enough.... Dreams for the PS4 is basically such a thing.
So maybe it could work,.... its just, its vastly differnt from a 2D platforming Mario Maker, where it doesnt demand much of the designer.

Imagine being able to make boomerangs that burn bushes, hammers that turn normally unbreakable walls into secret passageways, blue flames that turn your enemies into ice, arrows that turn enemies into stone, etc, etc. All of the typical items could be given unusal properties and the entire nature of the game could be bent just like we're doing with Mario. There is some truly wacky stuff that could be done, like replacing the bomb explosion animation with flowers or atom bombs or whatever.

Yes, I have thought about a Zelda Maker for a while now.  It could be something as simple as creating and sharing your own dungeons for the original Legend of Zelda.  Something more ambitious would be able to also be able to tinker with the Overworld Map as well and create your own "Third Quest" so to speak.  Moving Shop, Special Item, and Dungeon locations like a do it yourself Zelda Randomizer.

A more complex creation process would be the only way it would work, and that is not a bad thing.  Many people just want to play the levels rather than create them, and it would give options to creators between using a simpler Mario Maker game or the more complex Zelda maker.

Anything other than that and yes, your concerns would come into fruition.  However I do not think that anyone who wants this truly wants nor expects a Zelda skin Mario Maker.

How about a Picross maker? I know Rol would spend hundreds of hours on that game. He might be one of the few buyers though. So in essence he could share the levels to himself.