It seems like there could be unexpected interactions with other services running on 127.0.0.1, which don't even have to be HTTP to cause problems - eg what if t

It seems like there could be unexpected interactions with other services running on 127.0.0.1, which don't even have to be HTTP to cause problems - eg what if there's a service that echoes back the request in the response if it receives a request it doesn't understand? A remote web page could probably use that to bounce its request to your service but appear to come from 127.0.0.1.