Matzy, I give up, you don't get it, the end. I get it, I think its one approach to narrative in FPS and one of the best, but there are others, clearly you prefer them.
One thing, though, your statement on freedom such as being able to fight for the combine is absurd in this concept. No game has freedom. Some work hard to give an appearance of freedom, but it's never really there. HL2 is absolutely linear for a reason, it's telling a prescribed tale, and you're living it.
To argue for anything else is just arguing for the sake of it. I might as well wonder why in GTAIV, which is actually trying to be a relatively open sandbox game, I can't decide simply to turn my back on crime, work hard driving taxis and get married. I can't because the game's narrative has already been written.
Sure, some games say - you can be good or evil, or you have two choices instead of one - but those games want to offer that and HL2 doesn't, and no matter how many choices you think a game is giving you every one of them is preset. No freedom. Nada.
Actually, one other final thing, all the blanks that Valve want you to fill in (remembering they are deliberately keeping certain elements from you) can be if you just look around and think.
Try to be reasonable... its easier than you think...
