Having the PowerPC RISC-based chip really wasn't really a big reason why the Wii U doesn't have third party support. Looking back at its conception to now, it seems the machine was doomed to fail after the partnership with EA failed, and I don't think it was because of the rumored rejecting the Origin store front, its a good chance it was the deal, that eventually fell through, with Microsoft and it's orginal plans for the Xbox One.
The next big blow would be when the major game engines at the time, the CryEngine and Unreal decided not to actively support Nintendo's home console. With out that support most developers didn't seem to want to spend time setting up the engines to work with the console. Then there was the nasty spiral that was Nitnendo getting use to HD development so their games were pushed back and the system not selling because the "big titles" were late, then the thrid parties "testing" the waters with questionable titles, which caused some to pull out.
