I am not justifying anything here. Unless Bioware blatantly said something like "players will have complete control over what kind of ending they get, whether it is happy, sad or bittersweet based on the decisions they made", then I see players' complaints with that quote as unfair since they are only looking at their own say in the story and not Bioware's. What if Bioware had 16 vastly different endings, all with varying outcomes but all of which ultimately ended on a bittersweet note (or a tragic one if you rushed through the game and screwed up everything)? Would that have been wrong?