The "Jesus" thing in video games is lame. Ramming some post-modernisitc pseudophilosophical bullsh*t down everyone's throat at the end of a video game for the ending is lame especially given the "action movie" genre of the story.
Mass Effect has been posing questions and dishing out "deeper" moral dilemmas the entire time. You can't even get out of ME1 without throwing thousands under the bus for the destruction of one Reaper, and you have to consider galactic politics and the appearance of humanity, too, while a gun sits at the heads of the council. I don't agree with your assessment of the "genre".
ME3 didn't give you the feeling like you won. It was a feeling of loss at the end. A feeling of emptiness. What was the point in that? It might work in a movie, but it doesn't work in a video game.
I felt like I "won", but yes, it's tempered by sacrifice. Something Shepard's long acclimated to.
Hackett's association with the Japanese atomic bombs isn't without merit.
Of the three games I've played the story of ME3 the least of the bunch. I get to where I finish the Citadel DLC and why go any further? It's all downhill from there. After you take down Cerberus, the game stops being fun to play. It goes into complete downer mode.
It does? Priority: Earth is gritty, yes, but that's to be expected. I appreciate that they took the tone seriously, and the final battle is exhilarating.