Nintendo has stated several times that E3 was mainly for showing off their casual games. I don't blame them since that market is a cash cow. Look at Nintendo's recent incredible profit reports. Now as long as they will be using a good bit of that cash to finance some great hardcore games, I'm all for it. E3 isn't the only gaming convention out there, you know.
Besides, a new Mario and Zelda have already been indirectly confirmed. "Hardcore" gamers have nothing to worry about. Nintendo hasn't forgotten about the fans who helped them get to the top.