how more 'on par' could it really get? running some things better and some things worse = inferior?
The problem here is traditional expectations.
Generally the culturally inherited memetic in gaming is: every new generation is a zillion times more powerful than the one before it and makes everything before it appear puny in comparison. I think it's rendered down that simply.
If the Wii U doesn't run every 360 game at 2 times the performance or quality, it was always going to get trashed. If it actually suffers poor performance in ports - even if those ports were made under sub-optimal conditions - then the "ha ha, beaten by 7 year old tech" notion was going to take root and become extremely difficult to dislodge.
In a sense, it doesn't matter if the Wii U in reality could be measured as somehow "2x Xbox 360" levels. Let's say it actually is that. Just for the sake of argument. People hear that suggestion, and I think many expect it would run Black Ops 2 campaign like BO2 runs on a good gaming PC - locked a 60fps, 1080p, AA, etc. Because a lot of people don't seem to realize that their nice PC that can double the performance of a 360 build at 1080p isn't just two or four times as powerful as a 360. It's
ten times as powerful. It already is "next gen" as people use that to refer to power, and overcomes issues like mediocre ports, poor optimization, dealing with OS overhead, by sheer brute force.
Therefore, the Wii U could be a very nice piece of kit, with a lot of great stuff that will come into play down the road (like the nice lighting seen in Nintendoland). But it's still going to get laughed at. Naturally, Reggie's flustered, poor interview response isn't helping.