It does explain some of the major third-party ports being cancelled... Metro Last Light for example. Remember all the quotes throughout 2012 about the Wii U's unexpectedly slow CPU? I think even the Tekken Tag 2 team complained about it at one point.
But, specs don't matter. All that matters is game play, and whether or not you're having fun. That's what forum goers and the vocal online gamers forget about all too often.
Wii U's low horsepower for an eighth-generation console doesn't have a negative impact on it's sales potential to the mass market. 95% of the possible customer base doesn't know or care, and they never will.