I don't know how valid it is to see the Wii as direct competion to the PS3 or 360. I'm not sure how many of the people who bought the Wii would have, without that option, bought a PS3 or 360 instead. And among that group, I suspect there were many that actually ended up being Wii-S3 or Wii-60 owners. Do you disagree?
Regardless the PS3 still launched alongside the established and much cheaper X360. People may also have been waiting for the PS3 but decided to go Wii60.
Yes. And? What does the fact that the 360 was out a year longer have to do with the exceptionally high sales of the PS4 being due to pent-up demand for a new console?
You said "The only surprise for me has been how well the PS4 has been selling. It looks like there was a lot of pent-up demand for a next-gen console due to last-gen's extended length".
Which seems odd to me, you are suggesting the PS4 demand is so high because of 'pent-up demand' - but the X360 had been out longer and had better support for the last couple years (software wise) so in theory I would have said any 'pent-up demand' would be for the next Xbox.
I don't think you understand what it is I don't understand. If there is no other competition, than would that not be an *advantage* to the console selling under that condition? Therefore wouldn't another console selling more with (strong) competition be a better performance?
This seems to me the opposite of what you originally said which was; "I don't fully understand why selling more with competition is better than selling less with none."