It makes sense with something like SMASH and Mario Kart. The DLC really helps freshen up the game (including free content updates) and I think franchises like this would lose their "uniqueness" if they were to be pushed every year.
From http://www.gamespot....s/1100-6429682/
Speaking to Examiner, Nintendo of America's Scott Moffitt explained that surprising the player is a key part of its gaming experiences, which is why yearly releases aren't part of its strategy.
"We tend not to annualise our franchises, there's not a new Mario Kart every year," he said. "What we've tried to do with the Wii U is first, create a fully-featured, really enjoyable game that has something for everybody, has surprises that you'll discover as you play through levels, and it gives you a good amount of quality entertainment.
"For fans who love [Mario Kart], we've released extra content over time so that it keeps the game fresh and allows them to experience more than they could when they originally bought the game."
He continued: "That's the approach we take, rather than annualising the franchise, we are periodically releasing new courses, levels, and features that keep people playing. We see a huge surge in gameplay hours on Mario Kart when we release [new content]."
Nintendo's strategy differs for franchises such as Pokemon, however, where the company is more open to annual releases.
"If you look at the Pokemon franchise, we have released multiple core games for the 3DS. We like to give fans something every year, but [for] something like Mario Kart or Smash Bros.,there may only be one version of that franchise in the whole console cycle."
According to Moffitt, the decision to annualise a franchise is dependent on "the franchise, the developer, and what new ideas they can bring to [a] franchise to move the gameplay forward and keep [it] fresh," but "incremental changes may not be worth a whole new release."