Lets breadown DayZ as a simplified scheme of main factors in the game - Hunger, Resources, Zombies, Players,
I think getting the right balance here is the key to how will game play out - as a "deathmatch" or "survival"
It's a balance between the amount of resources in relation to hunger demands, amount and strength of zombies in relation to amount of players/weapons. It's all interconnected, nerfing zombies makes resources easier to come by, which leads to players not having a challenge surviving, except other players, that becomes the only challenge left in the game and we got DM again, Imho zombies should absolutely be a threat, at least equal to that of other players - this leadsto a situation where shooting down a players is no longer a simple choice, survival actually becomes the motivation, not fragging.