There is a very long history of US-east-1 being horrible. Just bad. We've told every client we can to get out of there. It's one of the oldest amazon regions, and I think too much old legacy and weird stuff happens there. Use US-west-2.
Been in us-east-1 for a long time. Things like Direct Connect and other integrations aren't easy or cheap to move and when you have other, bigger priorities, moving regions is not an easy decision to prioritize.
Also isolation is not as good as they would have you believe: I am unable to login to AWS Quicksight in us-west-2...