Yes and no.... Let me explain.
Technically the Wii used a better processor than the then current generation (excluding next-gen) of consoles, the original xbox, PS2 and Gamecube.
Whilst it wasn't as powerful as the New generation (Xbox 360 and PS3) it was still a more powerful than the generation it replaced.
The Wii U processor however whilst yes more powerful than the Wii, it is NOT more powerful than the Current Generation of machines it is set to replace (Xbox 360 & PS3) and likewise the next gen (Xbox 720, PS4) will be powerhouses in copmarison.
My point is that they didn't even go 'better' than the current gen with their new hardware. I never expected exponential leaps or powerhouse computing, but one would have thought CPU wise it would have at least bested 7 year old technology.
Look at the Wii now, it always felt dated and now-a-days looks and feels even more so. That was despite it having better specs than the generation it replaced.
The Wii U having 'less power' admittedly only in regards to CPU, compared to even current generation hardware, may look even more dated in another 5-7 years time compared to the disparity between Wii & 360|PS3 now when up against Xbox720|PS4 titles.
We can assume the next gen is going to last slightly longer than the current because every generation seems to last 12-18 months longer than the previous. So 7-8 years down the line, that choice of CPU could be a crippling decision.
Of course this is mere speculation as we don't know the true hardware of next gen, but if the 4-8 core machines with 8GB ram rumours are anything to go by - the Wii U is in comparison to the disparity|differences between Wii & 360|PS3 regarding memory and processor - even more behind than that...
We wait and see, but I am not convinced 100% Nintendo will win the next generation race even with a 12 month head start, if power wise they aren't even whooping ass over current hardware.
Also in the back of my mind is still the fact that 'the company that releases hardware first, has never been the victor in the console war of that generation', as long as I remember.
Still looking forward to the Wii U, I'm mid 30's now, my expectations are tempered by past experience. But we are in for an interesting 24 months anyway.