If not for his arrogance and smart mouth the Borg may have gone in some different direction in the galaxy and never encountered the Federation and countless lives and ships, at least Federation ones, wouldn't have been lost.
Hadn't they already assimilated Seven of Nine's family at that point though?
That's one big piece of retconning!
I never watched voueur or Enterprise so if there was something in those shows that showed mankind encountered the Borg earlier I'm not aware of it.
From the ST I know humans didn't know of the Borg and vice versa until Picard kept sniping at Q and he decided to show Picard how wrong he was.
If not for that who is to say the Borg would have headed towards earth. They might have picked a different direction to explore. If they retconned it in a later show that this wasn't the first encounter I'm not aware of it
"Q If we die here, now.....you will not able to gloat. You wanted to frighten us. We're frightened. You wanted to show us that we were inadequate. For the moment I grant that. You wanted me to say 'I need you'......I NEED YOU!"