Recent history tells us that mid-level selling games have had very little impact on the Wii U's bottom line over the long term. That's resulted in the perception that only a major release will change the console's fortunes. If the same thing happens with the XO, if Quantum Break and Sunset Overdrive fail to spur system sales, then you'll hear the same kind of comments relative to Halo and Gears.

Like others have been saying, it pretty much is the fact that those are the two titles people are expecting to really finally start reviving the momentum the Wii U only saw at its launch. Other titles aren't going to contribute much, not really as much as they would for competition. If MK8 and SSB4U fail to bring back some Wii U momentum, a lot of people will just lose hope for the Wii U in general.

Here's the thing;

Mario Kart and Smash Bros are two of their most popular series of all time. These are the two games they are the most hyped up about, and these are the two games that Nintendo has actually given a time span for launch (Mario Kart May 30th, SSBU Winter). X and Bayonetta 2 (being very far outside Nintendo's usual child friendly audience) will probably do rather poorly on a console that doesn't want 3rd party games. While Super Mario 3D World did fairly well in recent times, so many 3rd party developers are leaving the console in the dust because every game they make for the damn thing never sells over a million units and doesn't make its money back. 

That being said, the Wii U needs somethings to revitalize it's stability and try to regain the casual market now stuck on tablet or other devices. 3rd party ain't gonna do it, so what's left is the 1st party games that are in their fourth and eighth installments (SSB and MK) that tend to grab the most people from most other consoles (and particularly the Wii).

Oh, and I suppose you can thank the people who constantly go on forums and tell others to "Wait for MK and SSB to come out before saying the Wii U is bad."

Heres the thing though. WII U is NOT getting those games. Xbone IS. Thats the main difference between those two. SSB and MK8 are the biggest games coming this year for WIi U and the only games that are going to be moving consoles at all. 

As for e3, IMHO dont know about nobody else. Ninty hasnt had a great e3 in the past couple of years not compared to the comp. Hell they didnt even show up last year. So forgive people if they dont expect much from Ninty on that front.

Price drops. Xone has room for them. WIi U doesnt, they already did one didnt do much and they are still not making money on the system. Frankly they cant really afford to cut the price unless they want more losses.

keyword being annual. Not quite sure how you can compare. We expect AC adn COD games becasue those are yearly releases, been that way for years. Cant say the same for Ninty so why would one hold them to the same expectations?

We expect PS4 and xone to have huge holidays because those are systems that people actually seem to be interested in getting. Especially in the PS4's case, they still cant keep it on the shelves.

Those are the only two system sellers for the Wii U. Heck Xbox One cost twice as much as a Wii U and yet still sells significantly better.

Because past proclaimed 'system sellers' have failed to really move that many units, and these two are huge franchises that have potential to help the system.

the ones who say that are mostly haters.

gosh, 2014 means 2014.

When you buy a console, do you only buy it for one game? I'm with the OP. It makes sense that other games are important, just because they are another game to justify the purchase of the Wii U. I certainly don't buy consoles for one game, and I don't know anybody else who does. Now, if there are five games I want, and lets say Bayonetta is the fifth, then it makes sense that I'd by a console I'd otherwise not have justified buying.