Nostalgia and Novelty.
The year was 1981. In January of that year, I had only recently turned four. That's when video games became a blip on my radar. By that point, there was Pac-Man and other noteworthy gaming franchises being born...
...including a goofy, pudgy man in red overalls who jumped over barrels. His name was obviously Mario. His brother Luigi showed up in a later arcade game in 1983, then the two of them rescued a princess from a spike-shelled ox-kappa demon hybrid in 1985; making gaming history.
I grew up with the Plumber. My oldest nephew was using an NES controller as a teething ring. That's how far back my history (and my money) goes with Nintendo and its stable of game companies.
That's the main reason I'm really annoyed with them sometimes: signing on to SOPA--given the glut of FREE ADVERTISING gamers have given them over the decades, they really ought to cut their fans some slack. (IP piracy sucks, but the media companies are trying to swat flies with sledgehammers. Government/corporate fiat over the Internet is not the answer.) That, and their NoA arm doesn't think that Last Story will sell. (I mean, it's only a brand-new RPG from the creator of Final Fantasy. It'll never sell...?)
Having said that, you know what irritates me even more? Nintendo detractors. Aside from the ones pointing out legitimate stupid dick moves Nintendo's made over the past three decades (Nintendo's a corporation; dick moves are inevitable...), they mostly gripe about being "sick of Mario, Zelda, and Kirby"; they want to see something new from Nintendo.
Never mind that if they've lost interest in Nintendo's output, they likely already have Sony and Microsoft products to amuse them; why do they grouse on games they don't even play anymore?
I understand that nostalgia junkies are a problem for the gaming medium, but so are novelty junkies: those who crave "new ideas" for novelty's sake--the hell with whether the new property is any good or worth a gamer's money.
Mario is overplayed, overhyped, and overdone. All true. The problem detractors of the good Mr. Jumpman have: 92% of his games are very, very good, and well-executed. The other 8% are third-party horseshit with a Mario license, like Mario's Early Years.
You ask "What about Mario is Missing?", dear reader? Ah. The SNES version has a decent soundtrack, uses actual SMW sprites, and stars Luigi. The only problem with MiM is that the enemies are no threat to Luigi--that was annoying.
Brand-name recognition means something, especially when the product actually is high-quality.