Got to remember they're Sony's bitches, and in doing so they get all of Sony's middleware, developement kits, game engines, technical support and whatnot.
The long 3-year developement spans are heavily due to the fact that these companies didn't have the resources avaliable to develope for the consoles easily. Now that the game engines are made, developers are adjusting to the console they'll come down, along with the costs. They'll never be on the same scale as PS2 projects were, but they're definitely going down.