Of course it's about what you define crazy low power. I though the Wii was crazy low power for example. A 0.7 TFLOPs console would definitely have a noticeable leap over the 360, considering not only the tripling of raw computing power but also
And why is that? Last I checked the only available rumours had the next Xbox pegged had a SoC or a discrete chip based on an HD6670 and the Wii U at HD4830 (which is more powerful). Now you may not believe that (and I too think it's very likely the next Xbox 3 is more powerful), but based on actual evidence at this time it actually is a scenario that may happen. I'm sorry for trying to reason with actual evidence instead of "how it should be done" or "how it turned out last generations" (both of which are invalid), but these rumours are the only thing we have to go by at this point.
First of all, the rumor about 720 was about the early dev kits, not the final 720 hardware of course
I am sure that not even AMD will know the final design until late in 2012 or maybe a bit into 2013 and if 720 does release in 2013 holiday
And somehow IGN know the exact spec of the final hardware ?
And all that considering the rumor has some truth in it, which is also doubtfull
Sure many scenarios may happen, but the most probable is 720 beeing considerably more powerfull than WiiU, even much more powerfull depending on pricing and what will include in the package
Keep in mind WiiU is confirmed to pack a screen for every system, that is a huge additional cost, if MS does not have such a thing in the pack, can definatly afford some much better hardware for the same price and considering the year later release