While not being able to use bubbles in low sec/hi sec interdictors can be used for PvE everywhere. They can be used pretty effectively against npc's. For example sabre can kill belt rats easily, it does same dps than a PvE drake after all. Also low level DED plexes can be easily done with interdictor. So they are not really "pure 0.0" ships, even though at their best there.
So it might be actually worth of mentioning that interdictors actually have some use in pve.