They like to nibble, but aren't terribly hungry.

Haha, excellent point. These are some of the weakest zombies I think i've ever seen. They're stopped by just about any door in the entire world, and can literally be punched out of the way while posing no real threat. One character just walks into a line of them and starts swinging to get them out of the way. Once that happened they lost any notion of being scary or intimidating, which kind of hurt the movie honestly.


'Get yourself a real dog. Any dog under 50 lbs is a cat and cats are pointless' - Ron Swanson

The weakest zombies I've seen lately were in The Dead 2. You don't even have to punch them. Just give them a little push. I think these zombies, who were "infected" were conceived more like the World War Z zombies. They are a host for a rabid virus that wants to spread itself through bites and not the super-hungry living dead types that really want to eat you.

If the virus' "objective" (or "programming", if the biotech company was building a bio-weapon) was just to spread then the zombie bodies were just its spreading method. Of course nothing can survive without resources, so what would happen if all the bodies turned into zombies?
If the virus was a weapon then that would be the weapon's optimal goal (the maximum expansion of the virus). And since that virus would act as a true parasite, as any parasite it would eventually die along with all its host zombie bodies - presumably both humans and animals. The end.

p.s. The zombie people and animals would either die of hunger (like I said, nothing can survive without resources, not even cancer) directly or, when their hunger was high enough, they would lower their dietary standards and eat each other out.

Fanboy : a person who does not think while watching.

This is a good point. These zombies just get a taste and move on. There was I think one exception where they gathered around some body, but otherwise they would take a nibble and chase new victims...