the only reason we haven't left is cause they haven't told us to, the only base that has any sort of major angst against it is in Okinawa, and even there it's half hearted cause the locals make so much money off of it, and the government there is worried about if Kimchan is going to wake up one morning and interpret the sun rising in the east as a sign that he should launch a nuke at Nippon, not to mention China, and the fact that it's part of the post WW2 treaty where we agreed to protect them.
honestly I think it would be a good Idea to close most of them, but I reject the notion that they are the US (not so) metaphorically asserting some sort of dominance.