I find it somewhat ironic that Patrick praised the ending to Lost because of its focus on the characters, when the ending of Mass Effect 3 eschews basically all of the character development you had done over the past five years in favor of a wedged in artistic statement. ME2 got it right-- while the ending was the culmination of that game's story, the device used to conclude that story was firmly centered on your crew. It balanced plot with character in a way that resonated with most of their fanbase. And by its very nature it could be either triumphant or tragic. You can clear the mission with your entire team intact, returning to the Normandy like McArthur to the Philipines, or you can suffer losses, and finish your mission at the expense of the characters you've grown close to for the preceeding 40 hours. And all of that is based on your choices. It works.
There's nothing like that in ME3. All of the character development, all of your emotional attachment to the cast is suddenly superceded by this whole new conflict that you have to make a snap judgment on. It betrays not only a lack of concern for player agency, but a failure on the part of the writer to understand what his game is even about.