There's absolutely nothing wrong with making it clear that there were other beings more powerful than the Borg out there. Q even said so, he said the Borg were just one race out of many that were out there that the Feds would encounter. What was silly, was them being so scared in the first place because they'd already faced more powerful beings than the Borg in TOS and TNG. Nope, the Borg were never meant to be Galactic Enemy No.1. They were just supposed to be a reminder to the Feds that they shouldn't rest on their laurels. Q wouldn't have introduced them to something they couldn't defeat based on everything else we know about him. No, Guinan (who had experience in these matters) argued against Q that the Feds would prevail, and she was ultimately shown to be the correct one. VOY didn't go far enough, it should've made it clear that the DQ is loaded with races and Empires that have been (successfully) fighting off the Borg right from the Borg's beginnings and that they are not some kind of Supreme enemy. Just the introduction to the next tier of Civilizations the Galaxy offers.