The ps3 had a massive core userbase to tap into and the Wii U doesn't.
Lets look at the ps2/gamecube/xbox gen. There were 180 million gamers who bought an xbox/ps2 and 22million gamers who bought a gamecube.
The ps3 had a rough start which allowed the 360 to take a massive marketshare compared to last gen. But since the total potential customers is so huge there was enough room for both consoles to sell well.
Now with the Wii's case it seems pretty clear that it didn't really steal many core gamers from the ps2/xbox crowd. This gen there are 168million xbox/ps3 gamers. Only 10 mil less than last gen despite how well the Wii sold. The wii kept all the nintendo gamers and also managed to get a massive amount of first time gamers to buy the wii. This new market proved to be huge but has almost completely moved on. Most of these people are certainly never going to buy another console in their lives. Especially not a console without a super cool new gimmick. The wii u gamepad doesn't seem like anything special considering touch gaming is nothing new. So now the wii u's only market is big nintendo fans, gamers who buy every console, and little kids whose parents aren't willing to buy them the other consoles. This as we can see is not a very big market.
