Due to the lore, I've found an interesting topic surfaced by theory. A theory that the "true Humans" do not respect, support, nor accept the Guardians as their protectors.
Update: I forgot to include that there are some forms of Information referring to Guardians such as Saint - 14, whom was actually much respected and loved by the people of The Last City, but due to his obsession with the downing of the Fallen through a long crusade, he is no longer commonly mentioned, but only as a legend now.
Nevertheless, we've gotten some pretty good feedback regarding as to why. Maybe the "living Humans" see us as something tyrannical?
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We were created in the game to protect the traveler. Not the city. They know that our protection is superficial because the traveler is stuck were it is. They built the city under it so that we would also be protecting thwm.