I didn't make it!
I need to find a mod that dramatically increases zombie spawns. I like zombie hunting ;)
I don't think that anybody was specifically working on increasing one type of monster over others. Usually mods that have extra monsters and cut-out monsters increase the number of all of them and usually zombies are present in the beginning stages of the game since they are not that much of a challenge being fairly slow-moving. Still .. they are pretty cool and I can see zombie hunting as something interesting to many. I just remembered that I saw some type of hunters mod on one of the German Stalker sites .. can't remember where or whether it had zombies or not. Anywho, keep looking around :)