Because Nintendo makes everyone else buy their consoles to experience what they make. But on the other hand, what they make is only possible because they made those consoles. Look at pikmin 3 and tell me where can you play anything similar to that? Not even in a PC (though it would be almost there)!
The pressure on Nintendo to fail with the Wii U is because of stocks. That's all the stock market wants. Nintendo fails now that they are buying. Nintendo releases titles on every platform and recover part of their money, losing an entire profitable division, but still a very good trade for those that bought stocks when it was down. Sony and Microsoft stocks also raise because they lost a big competidor, leaving Microsoft as only option for casuals and ps4 the best option for core.
The wii U annoys these guys. No one wants to fight price when the entire market is already settled. PS4 and XBox one already have their agreements of pc architecture and multiplatform releases. Only Nintendo is there trying to provide a cheap console with good games!