Nintendo is saturated with 2D platformers. The announcement of another one would not be huge news. I would not consider Donkey Kong a top franchise for Nintendo, and Nintendo has exhausted Mario's name to the point of hilarity. I was also comparing Yoshi's Woolly World and Mario Maker to the top franchises of other companies, not just Nintendo. The only thing, in my opinion, that is on the level of something like Final Fantasy, Uncharted, or Metal Gear Solid is Zelda, and that won't be at E3.
I personally don't consider Splatoon to be a big game. It's a fun game. I hope it does well, and it's great that Nintendo is pushing a new IP so much, but it's not on the same level as the games I've mentioned. The reason I don't think Nintendo will have any big games is that they have not given any reason to believe that they are. I could ask the same about you. What makes you think Nintendo has big games to announce? Nintendo has chosen to showcase Mario Maker at the Best Buy demo, which is already a weird game to allow the public to try. Every game Nintendo is known to be developing is a smaller game with the exception of Zelda. The Wii U successor could be announced as early as next year. Any new game they could announce isn't likely to be huge, in my opinion. Even if it were something like Star Fox, it could be of an episodic nature with shoe-horned GamePad controls, something that would probably disappoint the few people who wanted a new Star Fox. To me, it's just safer to assume Nintendo doesn't have much than to expect the world from them.
Edit: What studios do Nintendo have that could be working on unannounced projects?