It may not actually be my favorite but I felt it deserved some love

I'm not really sure this is true.  Super Mario 3D World is an amazing game and I don't think that there were people on the fence for the system who decided not to get it because this wasn't a true 3D Mario successor.  The game scored very highly by critics, has a substantial amount of polish and detail, and provides excellent multiplayer.  More people need to face the music that for many gamers (in particular those lining up to get an XBoxOne and a PS4) platformers and colorful games in general, and specifically Mari games, do not appeal.  We can see it around here the way that many in tis community will reject Nintendo titles without even having played them almost on principle alone.  You're not going to win those folks over with a flashier version of the same thing.

Would the fans be rating it higher and would it be going higher on people's top lists if it were a truly large 3D adventure?  Absolutely. I just maintain that Nintendo's dire straits are not based upon a single game or marketing strategy, but rather the change of the market that's been happening since the PS1 first entered the scene coupled with the mass exodus of blue ocean customers to cheaper, more banal entertainment available on smart phones and tablets.

There's still a market for colourful games, as evidenced by the strong sales of Mario Kart 8, Smash Bros, etc.

3D World just played it too safe and lacked the wow factor that would have attracted gamers outside the Nintendo hardcore