I don't think it would take a whole lot, honestly. Hardcore players are actually pretty easy to please.
1.) If they had even *one* edgy franchise like God of War or what GoldenEye was to the N64 to go with Zelda and Metroid and Mario.
2.) A solid online network.
3.) Better third party support from day 1.
Would improve the Wii's standing with hardcore gamers a lot I think. Even recently it has gotten better, the announcements of SMG2 and Metroid Other M were well received so was Punch-Out!!
Of course some people will never be happy, but I think if Nintendo had those three things down pat, they'd get *a lot* less grief.







