Dues ex did the same thing. You could choose stealth, fps, melee. And it didnt make you site around for 10 hours under its bum while it **** story on you. You actually played the story and your action affected the storyline.
it made you sit around and cry from boredom every minute, at least the game play in mgs is fun. but i do agree with you on some level, mgs4 would have made a better movie