Unfortunately
Yes, this trend towards a graphical fetish is really awkward. It's almost like... people expect to get value out of a new videogame machine. Shocking, truly.
The Wii obviously had no great jump in graphics, yet the games at least changed core gameplay like Galaxy (unlike all the WiiU platformers so far until maaaybe Yoshi), or the Wiimote enhanced it early on already in games such as Prime 3, Excite Truck and Warioware. Yet, who needs the gamepad again? Apparently not Nintendo's 1st party studios. On top of that, more classical entries like Fire Emblem Wii and Mario Strikers at least enhanced the genre variety (alongside actual 3rd party support).
WiiU on the other hand has nothing except underwhelming ,,safe bet'' sequels, i.e. a bunch of platformers and minigame collections that show no innovation in gameplay, no leap in graphics (not one which would significantly surpass original Wii titles on Dolphin). As a next gen machine, the WiiU literally offers no value so far.
But Mario Kart at least looks stunning. And that is, after MK7 already looked great on the 3DS and the jump is still crystal clear. Even if the gravity mechanics turn out to be insignificant (which I doubt), it's finally a Nintendo game which would still at least fullfill one of it's duties as a next gen home console game, while the rest so far (of the titles Nintendo actually tried to push) falls flat in every aspect and there's no reason to upgrade from the 3DS or even the original Wii which cover the same experiences and more. Or maybe I'm just a graphics whore, I mean, I only voted a Sega Saturn port #3 on my GotY list.
DK doesn't look bad, it looks amazing and has a beautiful artstyle. But still Mario Kart is not ambicious, it just has the graphical update it needed since Double Dash.
DK looks like the Wii game, including recycled animations and all that jazz. They added some fur effect that's barely noticable during gameplay and the art direction so far is worse than DKCR. (empty canyons and mountains as backgrounds, lacking the amount of detail from the Wii game) As said above, Mario Kart still looks amazing even compared to an already great looking 3DS title not too long ago.