To further customize Service Catalogs, I think it would be beneficial to have the ability when customizing Service Catalog items, to be able to turn off or hide the "Attach Files" button. In cases where you're trying to have Requesters attach a file in your own attachment type file, it would be useful to hide the large default "Attach Files" button so that they don't attach files to the wrong area. I ran into a scenario recently where my attachment custom field has a condition set that needs to be met, in order to create a Process Integration workflow. Since the Requester skipped this custom field and attached it in the "Attach Files" button instead, the Process Integration tied to the custom field did not occur.
