When the Wii came out they never really talked about the system - Nintendo is portraying the "coolest" feature of their new toy. Once again, that's the one thing you actually touch - the controller. You're talking semantics when you talk about "oh it's just got a new processor and a new video card, that doesn't make it a new console".
What's the difference between the PS2 and the PS3? That's all they updated and gave it a slight cosmetic change. There's no difference there. It's a new console because it's new hardware and a new control system. I don't see how that's *not* a new console.
Being backwards compatible is not the same as forward compatible - I don't know any console that's "forward compatible" at all and I wouldn't expect games made for the Wii U to work on the Wii - especially those with HD graphics, it's simply impossible. There are still games produced for both the PS2 and the PS3 simultaneously and I expect the same will happen with the Wii and Wii U. As far as the controllers go, I wouldn't be surprised if they have a dock for Gamecube controllers like they do on the Wii right now but I also wouldn't be surprised if they decided to let the 10+ year old system finally die.
I'll tell you what the difference is between the PS2 and the PS3. It has hardcore gamers that like the games that are on the console. Console gamers like the feel of their Xbox 360 controller or their Dual Shock controller. This WiiU controller will definitely be similar to both of those while adding in all those new features (especially the screen). The problem will start when there are no games that appeal to the hardcore market. It's an impressive showing of features and hardware... with only the promise of games that will come to the console and at a significantly lower level of graphics and "precise" gameplay.
The only game that I think it will truly make awesome will be Zelda with the inventory system. Much beyond that, I will have to see games being played to see whether I will be impressed.
Console gamers hated - hated - the xbox controller and expressed the same doubts you express now over the next Nintendo controller about the 360 controller. It still looked clunky, it still looked too big, it still looked stupid. All of these things were being said some 6-7 years ago.
Did you watch ANY of the conference? Did you miss the various developers talking about their games being released on the new Nintendo console? Battlefield, Assassins Creed, and the entire EA sports lineup just names a few already "signed on" to the system.
Significantly lower level of graphics? In comparison to what - the unnamed and unseen future consoles that will not be released within a year of the new Nintendo console? It
will be the top dog on graphics and processing power when it comes out and will continue to be for the following 9-15 months until Microsoft and/or Sony releases their next console. The hardcore gaming community does not wait - they purchase.
This new console is Nintendo's attempt to grab back some of the "hardcore" (read: FPS junkies) gamers back. They will have the graphics. They will have a nifty new controller system that Microsoft and Sony will attempt to copy (just like the Wii mote) and they will have the upper hand in 5-7 years when they roll out their next console because they acted first.
Sony or Microsoft will have to unveil something out of left field to get the momentum back just like Nintendo did with the Wii.
I think the only true concern over the next Nintendo console is the highly unacceptable Nintendo wifi network - though Nintendo is claiming their network will be up to snuff with Sony and Microsoft. The question is, will it remain free?