While I certainly have my issues with the sequels, Mass Effect 1 was essentially the story of how humanity came to power and/or dominance because of how exceptional it is. All four variations on the ending basically revolve around this theme.
While it's certainly valid to miss the feeling of humanity as the underdog, which was largely missing in the sequels, I don't think it's entirely fair to blame the sequels for continuing in that direction.
Besides, I think the series turns that particular trope on it's head in an amusing way. "Yes, you're exceptional, but you'd probably be better off if you weren't."