Originally yes, Smash is for me the most important game coming out on Wii U. However I've since become interested in Mario Kart 8. Aside from Rayman Legends, I'm scarcely interested in the rest of the Wii U's library.
Same was true for Wii which I managed to get not long after launch and "Smash Bros Revolution" was still merely a Wikipedia stub, but I had become interested in other games soon after, including Galaxy, Twilight Princess, and later Super Paper Mario. I now have about a dozen Wii games that I really like.
When GC came out, I did want it for Melee, but I was also already interested in a lot of its games.
As for N64, I had gotten it before Smash Bros existed, and when I later discovered it I was captivated and got it as soon as I could. From there it started becoming my most played game ever, alongside Sonic 2 and 3K.