If someone responds to an email sent from a request (with the ref in the title) and includes an attachment, should it attach the attachment into the request?
Keep in mind that that full email is accessible from the timeline, including the attachments. On the Timeline entry you can use the 'More Actions' menu item and there will be an option to view the entire email. We have a planned change that will identify emails in the timeline that have attachments by displaying a paperclip icon. For quick access to the emails in the timeline, you can use the Timeline filter and select that it only shows updates of the type 'Email'.
The challenge with automatically adding attachments when using the Email Routing Rules is that it would add all attachments including those that people add to their email signatures. When we first looked at this we found that in a few short emails between the customer and the support staff that the attachments section was filling up with unwanted attachments, in some cases hundreds of attachments as the automated email updates were applied. At the moment you still have the opportunity to look at the full email and then save and upload just the attachments that you wish to include in the main attachments section.