Question

Do I even need this rule anymore?
I don’t see any requests incoming for resource.axd files (as opposed to when I ran webform applications)

Answer 1

WebResource.axd is an HTTP Handler that is part of the .NET Framework
that does one thing and one thing only – it is tasked with getting an
embedded resource out of a DLL and returning its content. What DLL to
go to and what embedded resource to take are specified through the
querystring. For instance, a request to
http://www.yoursite.com/WebResource.axd?d=EqSMS…&t=63421… might return a
particular snippet of JavaScript embedded in a particular assembly.

Its still part of the framework and you can still retrieve embedded resources using the above handler. You dont want your route handler to handle such requests and that is why it is ignored. My guess is that you can get rid of it if you are completely sure that your app/libraries that you use dont use it.