I think what really burns for me is that what's happening here is in many ways a reflection of the Mass Effect franchise concept: That if enough people come together to oppose a Great Evil, they can make a difference.
So Bioware has made itself the Great Evil, and we're all coming together. In a sense, the critical concepts of the series have migrated out of the game and into the real world. Unity, Common cause against Evil, and a Unified Stand against having something arbitrarily forced on us because someone else has decided it's in our best interests.
With this ending, Bioware have become the Reapers.
The problem with this approach - if this was the intention, is that it's alienating their fan base. If they don't fix this mess quickly, they'll wind up with such a negative viewpoint, that the next time they market a product to the masses, the response will be variants of, "Oh, them? You kidding me? They can't be trusted! I'll spend my gaming dollar somewhere else, thanks!"
There's also the fact that in becoming the Reapers, and uniting the people here against them, they've created the same situation that existed in the game.
If, in the end, they don't change anything, and what they gave us is the definitive ending of their game, the REAL message will be the following:
"There is no hope. Life sucks, you never really had any choice and it's rigged against you from the start."
That message is completely contrary to what the Mass Effect franchise has stood for over the last 5 years, including all throughout the last game, where characters are making life-sacrificing decisions to fight for a better future. It's what we're all fighting for here, as well.
I sincerely hope they produce some kind of additional material, and show that the endings we've seen are just "Indoctrination at work". Because the ending they've shown us is SO bad, that if it stands, they'll lose our dollar to their competition from this point onward.