My direct employers aren't currently making use of a wiiu devkit directly, my access to one is through a seperate softare developer we're close with, so my experience with the platform is limited.
I can say that with the right push the WiiU is capable of much nicer graphics than it's currently showing off (even better than those used in the xeno game trailer), but the current sdk version cripples what's possible because certain hardware aspects are either not well supported or dumbed down through the sdk, once nintendo updates the sdk to give better access to the hardware things can go much smoother, which is probably what the xeno game guys are waiting for.
With that said though, Nintendo have a tendancy to keep such software to hardware translations to themselves for first party releases to ensure superiority over third party software, leaving it up to the third party developer to 'hack up' their software to basically cheat the system, when we were working with the C we had to do similar things with the hardware to get it to do what we wanted because the sdk didn't give us the level of access to hardware we needed to do it properly.
It's only a speculation of course that they 'save the best for themselves' but in the past Nintendo *have* released several first party titles with a newer version of their SDK before making it available to third party.
