Mario 3DS and Mario Kart 7 will in all probability be great games, but neithre will solve the underlying problems of the 3DS software library. Despite what some people might say I think the stereo 3D on the 3DS is phenominal, yet the build quality of the system is rubbish.
If Nintendo were consistenly failing on all fronts they'd be much easier to hate. From a consumer point of view its a problem with them being both a hardware and software developer. To get the good you're forced to put up with the shit.
And even something like Steel Diver I wouldn't call a 'miss', at least not on the same level of true rubbish like Donkey Kong Barrel Blast. Steel Diver, at its core, was a great concept, if very niche. But Nintendo fucked up execution and value of the package. Its a prime example of having something good and screwing it over, in turn screwing everyone over.
@Omi: As a whole, I think Nintendo's hits outweigh the misses. Not all of their software is AAA brilliance, but most of it is at least above average and worth a look, and littered among these titles are true gems.