I actually spent several minutes trying to figure out how to display the context menu to delete various objects in workflows, or file/directory names in search scopes until I realized that I the delete key works.
So it would definitely help to be more consistent in the UI: some lists have little "+" and "-" tabs to add/remove items (e.g. Themes), some only have the "+" (e.g. Search Scope), and some have neither (e.g. user defined file types). And some have context menus (e.g. Themes, but it doesn't include the Delete action), but most don't.
Not a big deal, more a "polish" kind of thing...