And even that was, itself, a big ass retcon that was one of the biggest flaws of the series. Not only did they walk back the recognition of the Reapers for a denialism that served no overarching purpose- the Reapers could be overwhelming no matter how much we prepared- but the stasis they put the core plot into was the one that made the Crucible and it's abruptness as a necessity.
After ME2 and a lack of preparation or set-up for how to beat the Reapers, ME3 was always going to involve either a keystone army or superweapon gambit that would beat the Reapers, tied into the ME tradition of some sort of Final Choice.
The Reapers were handled in an idiotic way, absolutely. ME1 sort of - just barely - set up a concept that could have worked: the Reapers, despite their ridiculous bond villain nature, are clever. They divide and conquer the galaxy, fighting as a massed unit with superior technology against isolated forces, using mind control to control and repurpose enemy troops, etc. This is about a chessmaster that pretends to be powerful.
Then we suddenly have Sovereign being full on invincible without - for completely insane and inexplicable reasons - doing the one thing that makes it vulnerable! For no real reason. Yeah, OK, he's locked out of the Citadel. So what? He's got an army of Geth and clearly can just nuke all of the Alliance ships out of existence
If they stuck with the idea that the galaxy could win against the Reapers conventionally, if at least at great cost, then we'd get some measure of satisfaction out of the plot.
Though I really think with their set up the plot should have been about this basically race-based Trimuverate ruling over the galaxy with an iron fist, which is basically what the Council does really.
The thing is, no one would even want to play through a game where the setting doesn't change substantially. No one looks at the boring parts of history - where absolutely no notable event happened - and thinks, "this time of stability, economic wealth, social advancement and political growth is the perfect time to set my fighting-based video-game in."
Even games that are lauded for their "small scale" plots involve substantial and radical change, at the very least political and social if not metaphysical.
I agree with In Exile. Not to mention that humanity is already on a different level compared to the other MW species. No other specie achieved a citadel embassy as quick as the humans. They managed to fight back the turians in the First Contact War. Their rise after the Mars Archives discovery was incredibly fast, and despite the differences in centuries and thousand of years compared to the other species they build a strong army and fleet, quite advanced, and they were increasing their number, up to the point that only the three Council species were superior or at the same level. They co-built with the turians one of the most advanced starships in the galaxy. Even the chance of having a Spectre was incredibly fast, and no other non-Council species had that chance. Even the turians didn't have one before they helped in the Krogan Rebellions.
The thing is, the original idea of ME - totally abandoned by ME2 - was that the series was about the ascendancy of humanity. The Reaper plot was the B plot. The point of the save import was to allow you to carry over your influence on humanity's political growth - whether we become the Federation or the Empire. But that all got dropped between all the random sci-fi cameo style missions of ME1 on random worlds, and of course ME2 and ME3.
10 points to Gryffindor.
I always thought that Mass Effect as a setting showed huge promise, but the devs by and large squandered it as they went. The biggest mistake was of course the reapers themselves, who were such an absurdly powerful and setting-destroying force that unless they piled on the plot devices even more than they did, they would inevitably trash the Milky Way into an unrecognizable mess.
Whereas in turn, Dragon Age started as the most bog standard of fantasy settings, and their writers managed to make it work as the series went on and they added interesting new lore.
Mass Effect had some great small-scale stories, especially in ME2. But the overarcing plot really wasn't anything to write home about in any of the games. Let's not kid ourselves.
That's why ME2 was so great. Yeah, it derailed the main plot, but it was also smart enough to realize that the main plot is always going to be stupid, so they might as well have less of it and end with an bad-ass final mission.
Seriously, if you just swap out the "Collectors" with an actual pre-invasion by the Reapers, Cerberus with the Alliance, and you end with nuking the "Reaper" base, the game basically is the same except you add some tension to the plot and move it along for your resolution.