I think the big difference between this and just 'being able to' do the same thing with a tablet is the same as all consoles and their horrible specs, but somehow decent looking games. Developers will know the exact specs of the target machine. They will know that every user has this exact controller. This will allow you to squeeze every last inch of power out of the system without worrying about people with less powerful tablets and phones. Tablets of that caliber are in the $400 range. And obviously without something like the OUYA, making an android game at this time under the assumption that your userbase will be using a controller is silly.
The graphics of the tegra 3 are easily beyond the current wii:
The extremely low price combined with just 1 or 2 killer apps could just be enough to make this a viable platform worthy of both developers' and gamers' time. I definitely think they should beef up the specs, just to make it that much more appealing. Hopefully the insane amount that they'll end up exceeding their goal will help them to work out some type of deal with a hardware distributor or manufacturer to keep the price in that range with something a little more exciting hardware-wise, not to mention some much needed advertising.
In any case. I've been completely bored and frustrated by the state of current consoles. I think the outpouring of support is indicative that I'm not alone - and maybe the industry is ripe for a new contender.