The simple fact is this, people don't like change. Developers don't like it right now because it's different. It's harder in the short term. Newell wants to port games straight from PC to all the consoles seamlessly with no effort or work.
Sony went in a different direction. Other developers have had wild success with the PS3 in game play and graphics. Why can't Valve? They can. They just don't like change or working differently than they have.