Because at least latest news told us, that the good ending was already created.
I don't think 'created' is the right word here, we don't know at which stage they were gotten rid of and why. But it does look like at some point they were considered. So, not supposed to be doomed from the start, likely. Now, what came first - the writing decision to forsake those endings orrrr [insert whatever happened that caused Act 3 to be the most criticized part of the game], that we'll likely never know. The latter would be more promising for our hopes than the former.