If Voyager was built after BOBW and after the Defiant. Wouldn't Starfleet also keep in mind that if the Borg are coming that all new ship build after the Defiant would have to be equipped with defenses to fend off an attack? Why would they keep making ships that weren't safe and keep sending good Officers out in them? It's why they kept stressing how top of the line Voyager was and why it had gel packs to make computer processing as fast as thought..............similar to a Borg Cube. Without the Tri-Cobalt torpedo's, Voyager can't beat a Cube but it's designed to take a beating, defend itself and run.