Complaining to the FTC, eh? Well, certainly a legal privilege to do so and even though I doubt the FTC will pursue it to the fullest it does draw attention to the fact that there is a sizable number of people who intensely dislike the ending.
As for me, I've stated before how I dislike the ending, but I don't expect there to be a new one. Sure we might whine and complain, but...whenever Bioware rolls out their next RPG whether it be within the ME universe or perhaps a different one, how many of us whiners are not going to buy it because of our ME3 rage?
For as much as I disliked the ending, I found ME3 overall to be a very entertaining game and well worth my 60$, and I'm going to continue to support Bioware's future endeavors simply because of the 4 Bioware games I've played thus far (KOTOR, and the ME triology) all have been extremely entertaining and provided hundreds of hours of game-play. I think at the end of the day Bioware and others involved with the production and sale of ME3 are expecting most of their target clientele to feel the same way and personally I think they are safe in doing so.
Plus, my main beef with the endings was the lack of closure on the party characters and their stories. Probably done on purpose to save for DLC.
Perhaps something in the realm of...I don't know...erm...say you control Grunt in a few side missions where he and his team of krogan uncover a Salarian-Turian plot to create a new genophage or something. Replicate this 5 or 6 times with different scenarios for the other party characters (just had an idea of Jacob and Miranda teaming up to go after remnants of Cerberus, could give Bioware a chance to tell us more about the still shadowy organizaiton)
and you could almost have enough content to make another game.