I think Reggie has a different idea than us of what a "hardcore" title is. For Nintendo, I'd consider their core franchises hardcore for what they produce. Look at past games like Zelda: A Link to the Past and Super Metroid on the SNES. Those games hold up well even all these years later and still demand a certain level of skill to complete. When people who have been fans of Nintendo's first-party titles think "hardcore" this is what we mean.
Even today, LoZ: Twilight Princess and Metroid Prime 3 are still hardcore entrants into those franchises. New Super Mario Bros. Wii is even hardcore. It's classic Mario gameplay with a decidedly higher difficulty curve when compared to classic side-scrolling Mario games (Japanese Super Mario Bros. 2 not withstanding).
I think games with regenerating health, deadpan AI, and easy-to-get-through 6-10 hour Story Modes have made seasoned gamers soft while allowing the casual players to feel more accomplished for not really accomplishing anything. In reality, we've all been lumped into that blurry middle-ground.
There's hardly a game made anymore by anyone where there's a serious consequence to your progress for sucking at it. I firmly place the core Super Mario games in this category. There's always been a requirement of skill needed to not totally fuck yourself over during gameplay as far back as the original Super Mario Bros. on the NES. They've just gotten softer and more forgiving over the years since Super Mario 64.
A recent title that fits this is Demon's Souls on the PS3. This game hates you and everything about you and doesn't care if you're having trouble. Totally great and we need more games like this.
There was an action-platformer for the Amiga made by Traveler's Tales called Leander. This game is very unforgiving if you can't adapt to it's quirky style. That I would still be tempted to play it almost 20 years later is a testament to it's production. Everything about it catches your eye, the art style, the music, the gameplay, everything. I've been playing it on and off over the years since it came out and can honestly say I've JUST NOW beaten it for the first time.
If it were better known, I'm sure others would feel the same way about it but my point is that there are not enough games from any generation that have the longevity to stand the test of time and warrant gamers to keep going back for the enjoyment of the challenge.
Nintendo, I can safely say, can and should claim this accomplishment.