This is where criticism goes from being valid within the context of the universe to simply trying to pile on the nonsense. The plot is terrible on its own merit; no need to bring these comparisons. There are hundreds of themes in literature and film that are unique to specific genres (Sci-Fi, Thriller, Mystery, etc.) that repeat themselves in various forms. I'm sure TV Tropes has something good on this one. I do think that the Bioware writers are incompetent, but they aren't plagiarists. I could throw together a decent BSG versus ME3-Ending comparison if I wanted to, but I don't think there is anything worth considering from that juxtaposition. The fact is -- though I can think of nothing off the top of my head -- there is probably another series (books, most likely) that draw from the same themes: a species fighting for self-preservation against a mechanized forced who they themselves think are doing ultimate good.