My confusion is the notion that "most fans" have reached some sort of consensus on this.
The game has been in our hands for just over a week. That's hardly enough time for the 1 million plus owners to have beaten it. Furthermore, only about 1,400 people have donated money to the charity.
Great, good for charity, but 1,400 donations hardly equals consensus.
Beyond that, the FREE TO JOIN facebook group has about 26,500 members right now.
If there are 1,000,000 copies of the game already in the hands of gamers, and there are 26,500 people who are unhappy, then you're dealing with somewhere between 2 and 3% of all people who own the game. Let me reiterate: That's 2-3% of people who are even willing to click a "like" button--one of the easiest forms of activism on the planet.
There's a good chance that, even if the numbers swell as more people finish the game, 70-90% of people are enjoying the ending.
If only 2.5% of people are mobilizing against something, there's a good chance they're in the vast minority. If that's the case, and I'm almost certain it is, then I can't imagine the gall it takes to demand something is changed that would cripple authorial credibility.
In terms of people complaining about choices made, I think (as I've said elsewhere) it has a lot to do with people assuming that the ending is only what takes place after the player makes his/her final input and before you reappear on the ship.
That's not true.
The ending of Mass Effect 3 starts just prior to the "point of no return" assault, it includes the chance to interact with various members of the story, it includes several moments along the way that are colored by choices made in the first two games.
I'm not sympathetic to this movement at all. It's not just because I'm a fan of the current ending. It's also that I'm not a fan of this notion of crowd sourced creativity. It's up there with voting "1 out of 10" at Metacritic to make a point.
You didn't like it. It was too bleak. So is life. So is the Christ story that Shepard is based on. So is nearly every catalytic change. If reapers dropping onto earth and killing everyone didn't set the tone for you, what were you doing for hours and hours of gameplay that didn't make you think: "this won't all end up perfectly?"
I wonder how many people would have petitioned Spielberg because Saving Private Ryan had an ending that was too bleak. I wonder how silly they'd have seemed.