Well there's also company contracts to take into account. For example there's usually agreements between studios and console companies to make console only exclusives which is why we'll never see a PC port of the same game. It's simple business. Console companies want to stay competitive and the way to do that is to make console exclusive games so people end up purchasing the console and the game. Without exclusives, a company like Nintendo will completely fold. Sony and Microsoft can take the loss of their game division, it won't be pretty but since both companies have other areas that they've invested in, they can survive the loss more so than Nintendo.
Console companies don't really make their profits off the consoles themselves, they make their money off of royalties that come from games that are developed and sold. In fact Sony operated at a loss when they manufactured the PS3, but made up the losses through the game sales. Nintendo makes a small profit from their consoles because of cheaper, lower powered hardware, but the profit isn't that big of a margin compared to the money that the games bring in. Then with DLC and online re-releases of classic games, companies can continue to make money.
With the growing market for cross-platforming, we're seeing higher competition because they're not only competing with each other but now also with the revived PC market. To stay afloat, they are trying to crack down and develop more console exclusive titles to compete with Steam and the huge indie game market that's opened up PC gaming to thousands of titles for cheap prices. Not only that, but indie companies have more of a chance of entering the industry through PC than consoles because there's less overhead and less clamoring to gain approval by Sony, Nintendo and Microsoft.
