Basically, you took something out of context a bit.

“The worst example comes late in the film, during the assault on the snow fortress-hospital. Cobb finally starts gunning down random bad guys, and Nolan interrupts the action to have Ariadne cry: “Are those projections part of his subconscious?“

(How has Ariadne forgotten this basic principle, one of the first things that Cobb explained?)

Cobb coolly replies, “Yes” (probably thinking, “I should have explained this two more times to her”).

Ariadne then cries: “Are you destroying those parts of his mind?“

Now, this is a fine question to ask, while they’re three dream states deep, and hours into a perilous mission (which followed weeks and weeks of planning).

But: “No, no,” Cobb assures her (and therefore the audience) “—they’re just projections.”

…What is this dialogue doing here?”

Well, to understand what the dialogue is doing there, you have to watch and see the next thirty seconds of the movie or so. Basically, Mal drops in, and Cobb hesitates.

So, at first he has no restraint in killing the projections, which the dialogue establishes, but when the projection looks like Mal, he completely freezes up. It shows the affect Mal has on his thinking, how his inner conflict throughout the movie basically causes him to mess up at the last minute during his mission, the external conflict. The dialogue preceding this, the dialogue you’re criticizing, establishes the juxtaposition. Now, you could say that juxtaposition is unnecessary or way too obvious, and that it would have worked fine without the dialogue in there, but you seemed to have missed its intended purpose in the first place, so it couldn’t have been that obvious, and it basically provides context to a major consequence of Cobb’s actions (not letting go of Mal), so it isn’t really unnecessary, either. You go on and on how it doesn’t make any sense for Ariadne to ask those questions then, and beyond that, it’s basically purposelessness for the scene at hand, when that isn’t exactly the case. You still have a point and all, namely why Ariadne asks the question when she could have asked it before (seeing how it’s a pretty stressful experience for the entire group, let alone her, being the most inexperienced one, I let the thing slide and gave it the benefit of the doubt, but whatever). But anyways, I think you used a bad example.

That was just something that really stuck out at me. Other than that, I enjoyed reading your criticism.

Later on, I ended up writing something on backwards chronology, in case that interests you.

Cheers!
Adam