I'm a filthy skimmer so in response to Spider Jerusalem:
While you do have a point, from what I know of it the developers intended the White Phosphorous moment to be optional. However, I imagine making such a moment optional was a bit too ambitious for the scale of the project, and in the end they had to make a choice. Considering a lot of what they were trying to say with this game, that choice was to make Walker a bastard.
It makes sense with what the game is doing, which is a sort of critique or analysis on the modern obsession with war games. I feel like a game like this is kind of needed right now, imperfections and all. In an era where everyone is trying to make a Michael Bay video game it's nice to see an attempt at David Fincher.
As for the write-up, man, it is so very, very rare that Yahtzee and I see eye-to-eye on a game, and I expected him to rip Spec Ops: The Line apart. It was nice to see him give it a positive go for a change.
One thing I'd like to note, also, is how they presented the White Phosphorous in the game. The first time you see it you have no control, just watch as it drops on a bunch of soldiers and burns them slowly and horribly. So your first introduction is "this is horrible stuff".
Then everyone objects to it, and then you are presented it in a horrible, horrible manner.
While you touched on this in the other white blob moments, it just feels to me an intentional choice to take a powerful weapon and make the player feel horrible for it. Contrast it with any other game that tells the player "Use the rocket launcher!" or something, and then pats them on the back with a chest-thumping "Oo-rah!" as if they're some sort of hero.
I think the developers of Spec Ops: The Line intentionally tried to make these two greatly different in their presentation.