It's not the case for me, their single player games are second to none, I love Mario (and Pikmin) and Zelda is my most hyped for game, I hope they do a Metroid and if so then I'll be hugely satisfied with them, the games I already have, and Xenoblade on the way!
Their problem for me lies in their multiplayer games. Here, where they used to reign as king, they fall short.
Yes, in local multiplayer they're great, but I don't live with my brother anymore and my friends aren't always round gaming with me. Nowadays online is where I game with my friends and without voice-chat it's just not as fun.
This is where they fall short, this is why Smash Bros and Mario Kart aren't as good for me.