"I think what would have helped the scene is if we (the player) had a better idea of the quantity of Alliance forces and their capabilities, and whether saving the Council *and* defeating Sovereign looks like a plausible option."
As another person already pointed out, the game intended for both solutions to be valid so in order to implement it they were intentionally vague. So no matter what you did, it was the right thing to do. When Miranda relates shepard´s action during the me2 intro, the developers used the same philosophy.
If you have an entire family of 4 individuals very injured after a serious car collision, with all 4 of them in severe need of blood, and you only have blood for one person, dividing the blood available to four will only ensure that all 4 perish. A competent doctor would need to triage and choose the one most likely to survive to receive the transfusion. it is wise to understand that there are situations beyond out control, and that we can not change them, no matter how much we may wish that things could be different.
" Presumably Hackett, Shepard, and Joker have some idea of this, but I myself didn't and I suspect most players didn't either."
Talking about awareness, the DA is sending a general distress call so any nearby ship can receive. Shepard´s communicator omni-tool also received it. They are not asking for alliance aid, since they´re not even informed yet that the alliance has just arrived at a mass relay that will allow them to arrive in just a second as soon as the relay network is re-established by shepard.
The aliens have a lot of nerve if they dare to say that shepard killed the old council. Saren and Sovereign had turned the mass relay network off. FTL speeds are still possible, but it will take A LOT of time so that one can say that each system is now closed to the others. If anderson and shepard had not rebelled, without the data obtained on illos from the vigil AI there would be no way to take control of the citadel once again and re-initiate the mass relays. If now for shepard, the person they grounded, the alliance would not even be able to arrive at the battle.
"The very first time I played the game, I thought that giving the "save the Council" order might mean I'd actually lose the game right then and there,"
It is a logical, responsible and mature assumption. or maybe it could cause fears that sovereign shall be able to invite or wake up a bigger number of reapers for the invasion that he would should the alliance be more expedient.
"and that concentrating on Sovereign might mean that we could still save the Council after defeating Sovereign."
Indeed. Maybe the DA will hold on. Maybe they will use escape pods or shuttles. I mean, they don´t have a mobile bunker, a resistant capsule like a black box from a plane for top-ranking people? Anybody remember the president at "escape from new york"?
"I don't think ME ever presents us with a dialogue choice that leads directly to a critical mission failure, but I didn't know that at the time."
The only way to die verbally is by letting morinth seduce you, but this can only happen after you beat me2.
But in blind plays, if we are playing seriously, we try to make the safer assumptions.
"enough ships to save the Council and still take down Sovereign."
All they know it that the reaper is measured by kilometers. But no one has seen one in action. it´s still a big gamble. On everyone´s lives.
"There are a lot of civilians on the Destiny Ascension."
Are there?
Somehow I don´t think such a sensitive military vehicle would allow civilians without a very good reason. I know that the volus on the wards spoke to the woman about being aboard once, but I presumed that the tour was a exceptional event. I imagine that most of the people, if not all, are officials as well as enlisted personal, or whatever system the asari use. I don´t even know if there are exchanging programs accepting turians and salarians serving inside the ship. It is fun to wonder if an asari facility has 2 types of restrooms, in case of poli-gender aliens decide to visit the place.
"They're going to need the Council after this battle is over"
They may need A council, but I don´t see as a necessity that they have THE exact same previous council. In fact, even if they survived (out of pure luck or because the alliance saved their necks) I think the most decent thing they could do is to resign, and take responsibility for the attack. They were careless and less than competent, to say the least.
I think the aliens themselves could ask for martial law. The military should take control. Building plans for the war is a top-priority now, as long as there´s time.
"if there's ever to be any hope of a united front against the eventual Reaper invasion."
So they can display the same wisdom and competence as before? I think I´ll pass, thank you.
If you saved them for me2, you should know that they were the most unreliable people for this job. 'oh, yes, "reapers"... we dismissed all this nonsensical crap long ago'. Tim was right.
"As a Spectre, her responsibility is to all citizens of the galaxy, including preserving continuity of government wherever possible."
They can be replaced. Easily, I suppose. In the case of the asari this may be a shock, given how much they can endure prior to a natural death. As for the salarian it would not take much, since it´s rare to find a salarian who lived more than the 40s.
"However, not all of my Shepards have saved them."
Same as I, who had multiple builds. Byt for my blind play, the one that I did with pure instinct, I refrained from saving them. But nothing personal.
"I haven't ever picked "Let the Council die," which just comes out as spiteful and excessively human-centric, but some of them responded with the "Concentrate on Sovereign" line for purely tactical reasons."
When I did a trilogy play trying to cause as much loss, death and tragedy as possible, i picked the renegade option. Same thing when I used a pro-human shepard.
One good thing about me3 is that paragon does not always mean saving lives, nor paragon means killing them. In order to ensure that javik and kelly will survive one must use the renegade option. If kelly and shepard are naive when it comes to cerberus, she ends up paying in blood.