Sorry to interrupt again, but an idea's been stronger than my resolve.
To the ITers who take BW word for true (truly only stating, not judging) :
before the game release, they repeated that you wouldn't have to play multiplayer to get the "best" ending.
If I remember correctly, you can only have like 7500 GMS. If you take the readiness of 50% (without multi), it gives you like 3800 EMS.
With that, the "best" ending you can have, is synthesis (between 3000 and 4000).
So my thought is that, for BW, synthesis was supposed to be the best possible ending.
And for those who got more, you had the "easter -fan- egg" of seeing Sheppard breathe, as a "reward" for having played a lot, solo + multi.
(EMS between 4000 and 5000 + TIM interrupt in the final scene OR 5000+)
But for this scene to happen, it could only be possible with "Destroy" since it's the only one where your body still exists ^^
Just a thought that has been bothering my mind for some time now

(and, BTW, it doesn't make me happier about the endings)