Why is Jack so important? I'd place food over medical care, since it seems apparent that no one can get their own food other than Jin and Locke. Also, Sun has some medical uses too.

Kate seems capable of getting her own food, as the gatherer to compliment Locke and Jin's hunting/fishing.

Did we ever see her getting her own protein?

Jack has already saved a couple of people and if Claire hadn't been kidnapped, would be helpful in her giving birth and shit. Ethan's her midwife now. If Jack hadn't been around, Charlie would be daid.

Sawyer would be dead for sure...Sayid no doubt would have killed him twice over.

Shannon might have been dead if Jack hadn't gotten her to breathe before the koala bear food took effect.

I'm not saying that Jack hasn't been useful. Just asking why he's more useful than the person that has been feeding the community (since everyone poopseats, and only some people have been ill or injured), or the backup feeder.

For me it depends on how much I know: what an observer on the island would pick up, or the audience's limited omniscience.

Hurley knows Kate's a criminal, Sawyer knows she makes Shannon seem sincere and unmanipulative, and only Jack knows both facts (and he is utterly clueless about how dangerous she is, whereas I think the other two at least realize that getting her really mad would be a Bad Idea.) To everyone else she's the strong trustworthy broad with good ideas that's been gathering fruit for everybody for weeks.

Locke, on the other hand, is the somewhat creepy survivalist guy who came armed with enough knives to put on his own production of West Side Story and rambles about visionquests and Destiny when he's not off by himself in the jungle imitating Colonel Kurtz. I know which I'd feel more at ease around.

As an informed viewer, I think I'd pick the same. I think someone who's dangerously off kilter when their personal buttons are pushed is a lot easier to predict and get along with than someone who has the vibe of a religious fanatic.

Matt,

I think Jack has an idea about how dangerous Kate can be. Unless he has lost his mind, he can't forget about how desperate the marshal seemed to find out where she was. He still wants to know WTF she did. And her deception won't easily be forgotten.

Did we ever see her getting her own protein?

No, though she did say she was a vegetarian. Maybe there's a secret soybean farm on the island.

I'd pick Jack over Locke or Jin because I'd figure the odds of Jack figuring out how to gather protein (and while fish and boar are definitely more conventional protein, grubs are a traditional and easily accessible form if you start suffering from deprivation) are a lot better than Locke or Jin learning how to diagose, treat, and perform surgery. If we are picking teams, he's definitely my first choice. Second would be Sun, as an all purpose all star -- extra medical support, food gathering skills, and generally very calm and practical.

I think Jack is more situationally important, but when you need him... you really need him. So, if I stay healthy, thanks to Jin who brings me food (although, it's unclear to me whether he's sharing with everyone), then Jack? Eh, whatever. But I might hurt myslef of contract a dread disease, and then I'd be looking for Dr. Hero, youbetcha. He and Sun together would make me feel marginally less afeared of dying from some horrible wound or disease. And Michael of the "Hey, let's build a viaduct [I don't mean viaduct. What do I mean? Oh! Aqueduct. That's it], whaddayasay?" seems useful. And cute. And Hurley would keep me from dying of boredom, I think. And they all seem relatively sane. Or, would to me at this point, I think. I mean, OK, Jin's a little temperamental.

So. I need a team to keep me happy. Huh. Wonder what I'd have to offer them?