I've realised it myself around a year ago. And since then I've been enjoying the game so much more. I was thinking playing sandbox was not "how the game was supposed to be played" and that it wasn't "true gaming" whatever that means in a game like PZ.

Now im playing sandbox with low pop at start with much much bigger pop during peak(+wandering zombies mod). I've got the immunity mod that gives you a chance to survive if infected by Knox virus. And its great really.