Why should there be a happy ending? Tragedy is probably the greatest and most satisfying dramatic genre. Would Hamlet be better if he'd killed Claudius with a massive sword in a boss fight, then lived happily ever after with Ophelia and his best bud Laertes?
I dearly hope that Bioware continues to thwart expectations and make things difficult and uncomfortable. Dull wish-fulfillment is for fan fiction.
Till Bioware still wants to earn some money, I really hope they are NOT doing this.
Not only because I'm a "Happy-Ending-Fan", but also because I don't want to see Bioware "dying". Your example is not mutch up to date: Top ten of the most successful movies: Only one or two have sad ending, rest of them have Happy Endings. 
We all should ask Bioware for a LOT OF ENDINGs, witch makes as many people happy as possible. If the people are angry or to sad about a Game ending, they don't buy the next game anymore (probebly). Less happy customers, less game purchases, less money. And if the don't sell a game, there will be no other one. 
The developers should be understandable enough to say: "We MUST make as many customers happy as possible!" And if there are a lot of customers unhappy with something, the developers should ask themself: "What was wrong?" And even: "What could we do, to make this people happy again?"
Playing a game should be a impressive game experience for most of the gamers. And cause people are different, so they ask for different endings. And Bioware should try to create a great game-history AND to make a bit selection at the end. I'm sure it is possible, without spending to mutch money on it.
Two points witch drag down Bioware's reputation: When EA take them over and the end of ME3 (and their reaction on the fans, after). And till today Bioware have the reputation to NOT really care about their fans / customers. They can write as many "sweet" messages at the end of Trespasser, till they don't care about all the people who are so sad about the ending of Trespasser ....
... all this "sweet words" have no value.
Seriously: Does ANYBODY really belive Bioware care about the sad & angry people here? And will do something? NOBODY here believe this, IF they know Bioware a bit. 
My personal resume: Bioware makes the best RPG games ever, with the most stupid endings (ever). They care not a bit about there customers (but this is typical EA). And: If a nother game developer ever would start to make games like Bioware they .......... let's just pray for this. 
I ask myself if Bioware would behave like this if they would NOT be part of EA ... ? 