I think it would be a good idea to enable Content Security Policy on Stack Exchange. With CSP it's possible to disable inline scripts, and that can improve security. For example, some time ago I found an XSS vulnerability in the Stack Exchange chat. I reported it and it was fixed, but that vulnerability wouldn't even be possible if inline scripts were disabled with CSP.
frame-ancestors: self
, it also appears various browsers may no longer be respectingx-frame-options