Let me paint a fact: Nintendo's entire modus operandi for the WIi U (and to some extent the 3DS) has been selling nostalgia.
NSMB everywhere.
Isometric Mario basically being the same as 2D Mario but with a Z Axis.
DKC Tropical Freeze, which isn't too far removed from the classic DKC games.
A Link Between Worlds relying on ALTTP nostalgia to sell its new ideas.
Pokemon X/Y's abundant gen 1 pandering.
And now we have Star Fox 0.
Except each one of those games you listed also did something significantly new more than they did pander to nostalgia.
NSMBU added new power-ups, the Baby Yoshi power-ups, Boost Mode, Miiverse functionality, and was the first Mario platformer to receive DLC, which also introduced playable Nabbit.
3D World introduced fully fledged four player multiplayer to 3D Mario, brought back multiple playable characters with unique abilities and expanded on the concept, had an array of drastically new power-ups, had Miiverse functionality, had lots of brand new bosses, and brand new environment types. Not to mention all of the gimmicks in each level, many of which hadn't been seen in Mario before. Also, the level design was more expansive than 3D Land, so 3D World wasn't just "2D Mario with a Z-Axis", it had a healthy blend of 2D and 3D Mario level design sensibilities, which felt fresh.
DKC is a sequel to Returns that builds off of what made the original good. Also it introduced Cranky Kong as a playable character. Also had more dynamic and cinematic level design, and introduced a brand new set of villains, and the level design went all out and was quite fresh for the series.
ALBW is a legitimate sequel to ALTTP. The game would have sold just as well if it wasn't, new ideas or not. I shouldn't need to go over all of the new stuff that game did, but it being a sequel doesn't diminish it. Linking it to ALTTP meant it was expanding on the lore of the series that already existed.
X/Y was the first fully 3D mainline Pokémon game, and introduced Mega Evolutions, trainer customisation, an array of new Pokémon, a whole new region that was aesthetically unique compared to other regions, and did some groundbreaking stuff for the lore.
Also you seem to be leaving out all of the new IPs we've seen on Wii U and 3DS coming from Nintendo.
Compare all of these to Star Fox: Zero, which is literally a re-imagining of a game that only just got remade anyway. Almost all of the lines of dialogue we've seen are right from 64. The levels we have seen so far are just like their 64 incarnations in terms of aesthetic. Even the big new gimmick, the transformations, is from a cancelled Star Fox game most avid fans of the series have actually played due to it's ROM being leaked and even translated.
The difference between all of these other games and Star Fox: Zero is that these other games either reference the past while building off of it, reference games that came out a decade or two ago, keep the references mostly as secrets or unlockables (meaning they are rewards that simply add to the new experience), and in all cases, the entire foundation of the game isn't nostalgic elements, they are just a small part of a bigger experience.
Star Fox: Zero has the same overall story as 64 (even 3D World had a new plot), same locations, same characters, and 99% of it's mechanics are straight from a previous game. The game it is a "re-imagining" of also just got a literal remake not too long ago. It's a much more jarring case than any of the others you listed, and those other games having a few nostalgic elements doesn't excuse the sheer lack of originality Star Fox: Zero has in every aspect we have seen so far.
Krystal's problem isn't being Fox's girlfriend, it's that she doesn't really add anything. Like with Sonic and how he has like 30 characters that don't do anything...
Sonic's problem wasn't too many characters, it was too many gameplay styles being crammed into one game.
Nobody had a problem with games like S3&K, Sonic Advance, and Sonic Rush. As those games had every character work under the same rough template, but with added abilities.
People have been asking for this for ages and still ask for it today.