Let me start by saying I am a hardcore gamer - have been litterally since birth. My earilest memories include playing a skiing game on Intellivision. I've owned an Intellivision, Atari 2600, Atari 5200 (yep - as soon as it came out), Atari 7800, NES, SNES, Game Boy (at its launch), N64, Sega Genesis, Dreamcast, GameGear, Xbox (modded), Playstation, PS2, PS2 Slim, PSP Slim (modded), NGage, FC Twin, PS1, GBA, GBA SP, GBMicro (SuperCard), DS, DS Lite (R4DS), and now there's a Wii in the living room. No 360 - no PS3 - just the Wii.
Now, I agree - the appeal of the Wii is not directed to the hard core gamers. The Wii is far less powerful than the 360 or the PS3. In fact, it would be far to say it may not be as powerful as last gen systems. But it is a gaming system.
Here's the thing - it's not about novelty. It's not about grandmas. It's about fun.
When I play Super Smash Bros. Brawl - I have a BLAST. Same for Mario Kart, and Sonic vs. Mario Olympics, and Guitar Hero III. These games, quite frankly, KICK ASS.
I know, GH3 is not exclusive to the Wii. But it's there. And it's fun.
And there are hard core games for the Wii. Twilight Princess, RE4, MP3, SSBB, Manhunt 2, No More Heroes, The Godfather, Disaster... And, of course, hardcore games from the GC are playable - Killer7, MP2, MP, Soulcalibur 2, Rogue Squadron, Twin Snakes, Beyond Good & Evil, Eternal Darkness, etc.
For every Wii Play - there's a MoH Heroes 2 - for every WarioWare - there's a Okami.
And, yes, I called Brawl a hardcore game. Because it is. Forget Sonic and the Ice Climbers for a minute - if it was just people like Snake and Ike and Link (not toon) and Samus and Pit - it would definitely be considered "hard core". So, I don't see why adding Pokemon would change that. It's still just as fun, just as challenging, just as beautiful, just as feature rich, - now only more so.