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phalanx
Since: Jun, 2012
Asherinka
Since: Jan, 2018
molokai198
Since: Oct, 2012
The longer a given "bad guy" country/species/organization exists in a given setting, and the more we learn about it, the more sympathetic that group will become, until some or all of them inevitably either turn out to be/turn into "good guys", or at the very least they're revealed to be a group of Anti-Villains.
As for why this happens, it's probably because a writer wanted to create an Always Chaotic Evil race as a cheap source of antagonists, but then they realized the Unfortunate Implications of painting an entire group of people as morally bankrupt, and thus decide to give them a more nuanced portrayal.
The Horde from Warcraft, the Klingons from Star Trek, the Geth and Batarians from Mass Effect, and the Church of the Broken God and the Sarkic cults from the SCP Foundation are all good examples of this phenomenon. The Great Politics Mess Up forcing writers to replace Soviet villains with Renegade Russians might be considered a sort of real-life equivalent.
Edited by phalanx