The Wii has been on the market for about 6 years and was overwhelmingly dominant for 5 of them.My perspective on this generation:
Nintendo - repackaged hardware, "innovative controls", mitigated development risk, leverage on mascot based exclusive franchises
Result: Massive early sales and public hype, early eol for the console (dwindling sales of the wii, heavily decreased growth)
MS - rushed console, costly early issues, well supported online functionality, paid timed exclusivity
Result: seemingly most stable current generation but not without (avoidable) major expenses
People need to get it in their heads that the Wii didn't start fading because of a lack of power. It never had the power to attract 3rd parties for 5 of those 6 years it was successful. The Wii has faded in the past year solely because nintendo has stopped providing major support for the console.
Consider what perception of the Wii had been like had the Wii U launched in mid 2011 - 5 years is slightly early for a new console generation but not considerably so. No one would be talking about how the wii was supposedly front loaded.
As for the 360, it has always been relatively stable but it did not start outpacing the Wii until kinect launched. Its recent success has more to do with casuals adopting the platform due to kinect than how advanced the hardware was back in 2005.