You're right, I'd still buy a standard console from Nintendo to play first-party games, but I'm a diehard, lifelong Nintendo fan, and our numbers have been dwindling. I do think Nintendo can pull in more people than just the true believers by doing something fresh and unique. And what about new users, the next generation of potential Nintendo fans? Will Nintendo lose kids if they have to charge as much as the other guys for comparable tech?
Setting aside the Wii U Gamepad for a moment, I don't know how anyone can look at Nintendo's past successes and suggest it'd be wisest for them to not innovate. The directional pad, shoulder buttons, four face buttons, analog stick, Rumble Pak, Mode 7 graphics, motion control, touch screen, dual screens, glasses-free 3D -- if Nintendo had simply made the "expected" console at any previous point in its history, think of what would've been lost!
But I get that people are afraid Nintendo will try something that doesn't prove popular, that gets in the way of playing games in ways we already know we enjoy, like motion controls sometimes did. But for every Wii Remote or Virtual Boy, there's a lot more of the good stuff.