You miss-understand. I never said that i thought the ending was "Great art", merely that the creators had the right to their artistic vision (good or bad).
And the existance of this (or any) thread proves nothing except that people like to discuss topics (sometimes violently). But I do agree that a fair amount of people were disgruntled about the topic.
I don't think anyone wants to take expression away from the artists. However, I don't think you can change your art form at the conclusion of a ~100-hr trilogy and expect people not to tell you it sucks. ME3's ending literally breaks gameplay, lore, and characters that have been built over three games and several books and other media. Imagine da Vinci painting the Mona Lisa, then when it comes time to paint the face he decides to use surrealism style (think Dali's Clocks). It just doesn't make sense and it doesn't work.
To me, the art of ME has never been the story. The story is fairly cliche, derivative, and done many times before in Sci-Fi. ME's real art form was the ability to integrate the player into the choices, which had real, varying consequences (that impacted subsequent games) and deep character development; I honestly cared more about what happened to the NPC characters than I did Shepard.
Up until the last 10-minutes, ME3 continued this art form extremely well. Choices made in the game and previous games mattered greatly and character dialog/development was great. Then came the ending.
The out cry isn't over the fact that we didn't get the exact endings we wanted. Everyone's upset by the fact that ME3 continued the pace previously set, and was on track to be a great game with a fitting conclusion. Then, all of the sudden, it's like a different game. None of the previous choices mattered, the final consequence are really all the same (and they all suck), and we don't even get any dialog in the ending scenes, much less any resolution to the other characters/story-lines.
Unlike other art forms, you have people that are personally invested in their characters, the decisions they made, and their ME universe. People spent a lot of time (and money) over several years in the franchise. And to have it end this way...it just doesn't make sense. That's where the anger is coming from.
Maybe this clarification DLC can fix it...but I'm not holding my breath.