There is one last social consideration to take on board, before we move into the realm of the physical.
When the zombie apocalypse comes (we're so past 'if' at this stage), we will have hard choices to make. Do we lay down and play dead, then get back up again and eat our families? Or do we fight back?
On the most superficial scale, that's asking if we stand up for our beliefs. If all of society appears to be thinking Wrong Things simultaneously, then do we put our heads above the parapet and speak out against the crowd?
That can be really hard. It can involve standing firm against peer pressure and making your mother cringe. It opens us up to ridicule, at best, and prison or assassination at worst.
Or we can side-step all thought of that and just kill zombies instead. Staying silent, but watching movies, reading books and playing games, where we symbolically speak up by shooting zombies in the head by proxy.
On a deeper, more primal scale, it's stepping away from the veneer of civilization. It's letting our bestial, murderous tendencies rise to the fore. We are human beings, probably the most vicious, brutal, dangerous creature to have ever stalked the planet.
We smile as we kill. We plan it. We don't just kill for self-preservation or food. Look at our history and you'll find that we, as a species, will commit genocide on the flimsiest of excuses.
As individuals, we might believe ourselves to be good, wholesome people, who wouldn't hurt a fly. But if we didn't collectively stand by and watch other people do it in our name, then the world would be a much better place right now.
Zombies allow us to stop lying to ourselves. They are sort of human and we kill them en masse. It's them or us. Just like it's always been.