Take it from someone who has been there. The ending triggered a pretty significant depressive episode for me. I'm still pissed about it, and I will continue to badger BioWare for rushing ME3, the inane ending, and the inept way the situation was handled. I will continue to curse John Riccetelo and the rest of the heads of EA. And if EA does eventually go down in flames, with some better publisher who actually cares about making good games picking up the pieces, I will push for a rewrite of the entire game (since there were so many more problems than just the ending).
But that's all a pipe dream. Rant about it, get pissed about it, stick to your guns and if it means that much to you, never spend another cent on any EA product. But with the situation the way it is, you could throw enough money to pay off the US national debt at them, and you would still get an unsatisfying ending. EA won't let BioWare admit there's a problem with it. At this point, any movement, any give, means admitting they were wrong. It means admitting that they pushed a product out the door that wasn't ready. It means admitting that the writers' vision wasn't what they claimed it was. They have to stick by their product, or they have to admit they were wrong, and they can't do that now without losing even more face.