This was discussed during The Talking Dead. While it's one way to get the zombies away from the fence, it can also attract other zombies. Additionally, it can attract other humans, which they really aren't too keen on doing.
I'm thinking not everybody here is watching Talking Dead after each episode. I'd hate to think it's required, but it sure is handy.
The kids didn't feed the zombies, because the flashlight angle was too high, unless the lugged a ladder out there to do it. So it's expected to be an adult who's doing it.
From episode one:
The "not right in the head" girl didn't name Nick. That was the name on a badge on his shirt. Thus, the girl called him Nick. Which then instigated the other kids to start naming the other zombies (not realizing where she got the name from).
Carl, having just been chastized by his dad for naming the pigs, goes alpha-kid on them and lectures them on not naming the zombies. Because he's so experienced, and when he tries to boost his credentials by challenging them on "have you ever killed one", he's shot down by the girl who says yes. Because really, at this point, who hasn't killed a zombie? Pretty much nobody.
What's lost by a chunk of audience from that scene is that the girl is realizing that these nameless hordes did indeed have names. they were people. This scene is chock full of symbolism and stuff.
Anyway, watch Talking Dead, get extra details and clarifications.