I originally bought ME1 (before it was ever a huge friggin' franchise) because I always saw that it was a nod to some of my favorite old school sci-fi. Jack Wall's music, the computer interface designs, the lens flares, film grain; story aside, I found that the box presentation harkened to my inner sci-fi nerd in ways that I really enjoyed.
That's not plagiarism, that's an homage.
Now here's the thing about sci-fi: it's all the same dang story, with the same dang stock characters. You can draw parallels between Mass Effect and Star Trek, B5, Stargate, Halo, Blade Runner, and pretty much every other old school sci-fi story out there...that's called being in a genre. Before Legion, there was Data. Before Shepard, there was Picard, or Kirk. Before Grunt, there was Worf. Before FTL, there was Hyperspace. Before Mass Effect's skintight plastic-looking armor, there was...other skintight plastic-looking armor.
I honestly don't think the Mass Effect writers when devising ME1 were exactly striving for the cusp of originality: there's better ways to go about it than by living in the same stock vision of the future as has been done a hundred times before. I always felt like the universe as they envisioned was a nod to what I assume was their favorite stories/environments from this genre when they were growing up.
You're not going to knock Kill Bill for plagiarizing Karasawa's films, are you? ...And those even used the same camera angles!