Staff Lt Alenko, I'd just try to correct one mistake you make. A lot of people use the word epic, but don't know what is an epic story. They don't know because they didn't read the Odyssey, Iliad, Romance of the Three Kingdoms, or stories from the middle ages. The problem is that people only know fantasy and American movies. These two sure are "inspiring and triumphant" but they are not epic in its original meaning. Mass Effect is epic, the ending is epic. It's not the way you understand the word epic, but from the establish meaning, it is.
Thank you, but I did mean "epic" in the original meaning of the word. Mass Effect is epic, as if in it is a part of a sci-fi epic genre. The "ending" is incompatible with that genre, the fact that it struggles to be an ending at all notwithstanding.
Putting the wrong words in my mouth, Alenko, but I know that's easier.
Yes, ME3 was "grim", but the series has set up the Reaper extermination to be as such from the very first game, and BioWare is to be commended for getting the content this close to what was foreshadowed while still structuring a story that led to the Reapers' defeat. As HYR posted and in relation to the rest of the lore, it could have been much worse, and likely should have been. Calling ME3 "grimdark" is laughable, considering the threat was defeated and the player was actually given opportunities to take down a handful of Reapers on their own. That was almost generous, in fact, and offered moments of triumph while realizing a feasible solution (despite being roughly handled by the writers).
As for the elements I mentioned about how ME2 abandoned ME1? Eh. Look at the MEU and MEU v2.0 after the two-year resurrection however you'd like.
Believe it or not, I'm not trying to put words in your mouth, I am trying to convey how you are coming across in my view. You keep focusing on how BioWare set up the Reaper extermination and how they tried to stay true to that setup, while I tend to focus on that they have also set up the theme of the games as being triumphant against insurmountable odds and Shepard as a survivor. You claim it should have been much worse, I claim the exact opposite.
Also, I'm not calling "ME3" grimdark, so this time around it is you who are putting words in my mouth. Also, while I have resorted to quoting ME2 (gasp!), you are resorting to patronizing and condescending (the bolded bit). *shrugs* In turn, I shall now resort in turn to posting a silly picture:

Finally, as for those elements of ME2 you keep mentioning: I am looking. And I see no "MEU v.2". I see plot holes, sure, but no dealbreakers. Nothing that isn't a concious decision which has its cons and pros. The ammo retcone gave us faster-paced gameplay. Cerberus railroading gave as TIM, who is a compelling character and works gloriously as a guy you love to hate. Et cetera.
I think the game could have stood to be darker, particularly in how it handled indoctrination. We should have had to kill sympathetic people, maybe even a squad member, instead of Udina or TIM.
I actually agree - it could have been made consistently darker, which I wouldn't have liked, but it would have been a clear tonal decision. Instead it is a mess, a whiplash of dark (often needlessly or stupidly or badly written dark) and hopeful (likwise).
Oh and I like Udina! And I mean ME1 Udina. You know, the one that was a complete jackass, but did his job and had some gloriously hammy lines directed at the Council like: "This is an OUTRAGE!" or "SEND YOUR FLEET IN!" *clenches fist*