Are you seeing this behavior in a local development environment or in a (pre-)production environment? The public application root URL setting is a fallback for when the hostname cannot be determined from the HttpRequest's Host header. So for example when running on a cloud node you should not be seeing localhost:8080, but if you are testing locally then I believe there is no cause for concern.
I can see in the code this was changed but I don't know why, I will get back on this tomorrow after I talked with some people.
I'm experiencing the same problem. Has this been solved already?