I dont think that the Traveler truly does anything other than provide shade. Humanity decided that they were going to migrate under the traveler, and they built the wall there. Whether or not proximity to the traveler does anything for the city or its populace, i dont think we will know until launch.
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So... If I were a leader of advance race of aliens wanting to destroy guardians I would figure away to push the traveler down to squish the city underneath lol