I don't know if I ever really expressly felt that way on the mainline games
We had:
1. Ocarina- the original brilliant blueprint for all things Zelda
2. Majora's mask- yes, basically milking more out of Ocarina engine- but also a very different, more difficult, much darker tone game, just very unique, despite other "samey" core elements.
3. Wind Waker- rewrote EVERYTHING visually about the series so nothing repetitive at all, completely different overworld concept- fresh.
4. Twilight Princess- so yeah- maybe this is a nostalgia trip to the look and a lot of concepts harkening back to Ocarina after mixed reception to Wind Waker, but I never for a minute felt bored. If anything, I didn't like the wolf Link start, and it was major relief to finally get Link into his green suit with sword/shield. And when we got there, it was Zelda with the best dungeons of the series. I'll allow this re-tread because it was much wanted by the fanbase
5. Skyward Sword- obviously, completely different gameplay- personally I hated it, but it wasn't a retread.
Granted, it did astound me how much of a complete revision Breath of the Wild wound up being- I just assume it was going to be more of the same, just with the "large open overworld" trend that many things were starting to adopt, but they really did re-write the book on everything here.
That said for future games, there is huge room for improvement on that formula- better and more substantial dungeons more like old games would be welcome, more of a central narrative would be good, I'd like less weapon musical chairs, and more of a system of crafting and upgrades there (take some cues from Fromsoft here- let us take something we like and roll with it a whole game if we want via upgrading- and let us repair weapons - and certainly break a whole lot less))