Both the Wii and the 3DS are basically on the same level as the PS2/Xbox/Gamecube generation consoles.
Not significantly upgrading hardware power in favour of focusing on other features while keeping a reasonable price was a good decision for Nintendo as the Wii's market leadership proves. Keeping the power of the 3DS two generations behind the generation of home consoles LIKE THEY DID WITH ALL OF THEIR HANDHELDS might also prove to be a good decision.
I personally think that this unusual constellation with the new Nintendo handheld being on a similar power level (lol) as their old console could turn out to be a great advantage for both systems.
The 3DS can feed of even more developer experience and existing games then any previous handheld because not only are there games and experienced developers from the GC/PS2 generation, but game development under similar limitations went on on the Wii.
When it comes to the situation on the Wii, the system might benefit from finally having a proper multiplatform partner. Development of Wii/3DS multiplatform titles has already started with Rodea The Sky Soldier and some other games. I'm confident this might start a trend that will lead to more future Wii support then some people might expect.