You can use them with bits that don't have and/or can't accept bearings, like a spiral bit for example. If you are dovetailing with a jig then you need them for that too.
BobJ used to laugh at me for recommending Bondo for repairing templates, but it works perfectlyExcellent points. Another lesson learned.
Starting a bowl with a guide bushing and then converting to a bearing guided bowl bit saves wear and tear on the template as well.