Geth were explained to be a splinter group. True Geth are treated with a lot of sympathy. Rachni were expanded upon as victims of Leviathan manipulation. Krogans were seen as victims of a horrific war crime. The only ones not rehabilitated were Batarians, which I will give you.
Mass Effect is a reflection of post-9/11 banal liberalism, where multiculturalism is boasted and war is virtue-signaled against, but as always there are certain ethnicities who are inferior and thus oppression/war against is justified (Geth, Batarians, Rachni, Krogan)