Mario was never really "cool", he was fun and had great games. To me he has evolved into "iconic" status in gaming, the way that Mickey Mouse did in animation.

All I want is Galaxy 1/2 HD remake and Galaxy 3 to really show what the ol' plumber can do.

Have you guys been in a coma from 2006-2011? Mario is "cool" in the pop culture because of his retro appeal. Retro = cool.

The NSMB games and Mario Kart have sold a ton the last 7-8 years.

Everyone wants Mario in the next Wreck It Ralph movie.

The problem isn't Mario ... Mario is doing about all he can for Nintendo. He's not getting much meaningful help right now.

Mario related games are about the only thing that sell on the Wii U period. 

Actually I find Mario is considered "cooler" with adults than most gaming IP, even hipsters and all that.  

Wearing a Mario t-shirt is cool considering you'd get laughed at for wearing a "Kratos" t-shirt or something as an adult anyway. 

Mario halloween costumes are always popular with the college crowd too, I find almost at any big Halloween party you'll find even girls dressed as Mario/Luigi:

Just this week too, Dancing with the Stars did a big Mario themed dance number too:

https://www.youtube.com/watch?v=lK2lDKnjn6M

Mario is still very well known and well liked by adults. Nintendo's problem though I think is getting these people to buy expensive propietary hardware to play just Mario. It is a tough sell these days. They like Mario but they already get their gaming fix from their iPhone (especially women). 

He's so cool he's hot, and he's so hot he's cool.
Ancient Zen riddle, right there.

For Mario to be cool-er than he already is I need Super Mario World 3 on the Wii U basically.

3D Land doesn't count because it's a 3D game obviously and I want a 2D one god dammit!

I'm sorry...but I'm just going to burst Mario's cool bubble here.

Mario has never been "cool."

It's always been cool to hate on Mario. Those that have been fans have been fans despite people always claiming he was for kids. Even during the Nintendo vs Sega years Mario was made fun of. Nintendo fans have weathered the ridicule for as long as gaming has existed. In retrospect he's been looked upon fondly...but you never went to school with a Mario shirt and thought people were going to say "now that's a cool dude!"

Same as it ever was, Spurge. Of course, I've always thought the "cool" people were the ones that did what tehy wanted to, regardless of how people judged them.

Mario will always be cool among the oldschool

he's only uncool to the poor lost souls that didn't grow up during the golden age of gaming.

So that must be why the Mario franchise is the best selling of all time. 

The moment Sega of America decided to market the Genesis as the "cool" console and paint the NES/SNES and it's IP for babies, it was over. Mario has done well commercially, sure. But the imagine of being cool is gone and gone for good lol.

These girls grew up in the "golden age" of gaming? I'd rather hang out with them than the sweaty 300 pound unshaven guy camping out for Destiny while complaining about the last Hobbit movie or the dorky 14-year-old boys clamouring for "Calladooty" that their mom has to buy for them.  

If Nintendo put Mario on the iOS shop it would instantly probably be the no.1 download on the app store. Does anyone doubt that? Mario does suffer with insecure 12-19 year old "boys" who think they're cool by liking "dudebros" games until they get to college and realize getting laid is more important than playing video games. And then they get older and realize they had a lot of fun with Mario in their youth and that's "cool" again in their mid/late-20s. 

Women love Mario. Pretty much across the board.