I respect your answer but I personally have to disagree on this point, of course there can be moments in which you can only have one way or the other but IMO the suicide mission in ME2 was one of the best moments i've ever experienced in a videogame ever for the very reason that i can choose how it can end up, sometimes my shepard would be a hero and be able to save everyone, sometimes i'd roll a shepard who was more reckless and in so doing cost the lives of a few squadmates.
And this is the conundrum with the term "choice." You like it because you can "choose how it all plays out." I dislike it because I feel there isn't any really meaningful choice, for me.
Choosing "I'm going to make this choice even though I know it's going to be bad for this character" isn't really interesting to me. That's not to say ME2 didn't have positive parts. I mean, I lost Thane because I sent him in the tunnels, and that was cool. That was something where, if I looked more closely, I could have avoided and I'm okay with that. But everyone survived simply because I played through their stories and, in effect, earned their loyalty mission? It's not as interesting to me and emotionally falls flat.
Choice from the standpoint of "I want the narrative to play out this particular way" isn't as interesting as choice between "I'm presented with a choice and it isn't clear which one is the best thing for myself, my friends, or my goals." And I enjoy the consequences of knowing that sometimes, with the imperfect information that I have, what I think is ideal at the time ultimately doesn't turn out that way. An example is Bhelen vs. Harrowmont. I sided with Harrowmont, and as such probably made the bad choice overall even though, in character, it seemed like the best way to go.
I appreciate endings that make me think. Deus Ex (1) was very good in that, as was PST and Fallout1. The thing is, however, none of those games left you without hope for your character if you chose to play them that way.
You and I have very different interpretations of the PST ending.
An ending with no hope for the protagonist I will never like, but in a book I can accept it, because there can only be one ending and I'm not forced into complicity in bringing in about. The same situation in an RPG makes me rather rebellious against the writers, because I feel I should have at least agency enough to avoid the feeling that I'm forced into complicity in bringing about my own doom. Unless it's a noir story, but then you usually know that from the start, which makes all the difference.
This strikes me as purely meta, however. I don't see a conflict of player agency if the player's actions result in the player's death at the end of the narrative. Player agency, to me, doesn't mean "I am in control of what does or does not happen to my character" but rather that the game allows me appropriate responses to what happens in the game. The idea that the player can be placed into a spot, for instance, where performing an action results in their death is fine. But if we metagame and decide to NOT perform that action (presumably a type of inaction, if we're at the end of the game) I don't feel it takes away from player agency if it still results in the player's death.
Imagine a situation where DAO's narrative is different, and you're the only Grey Warden left alive (even more special snowflake!) and no dark ritual. I'd be a-ok with allowing the player to have the agency to say "eff this, I'm out" and allowing the player to choose to not kill the archdemon. I don't think it's a removal of player agency if the player still ends up dead as a result of this action. But I think it's safe to say that we probably have different interpretations of player agency and certainly different acceptance over what should and should not be possible within the context of a game in how it allows player agency.