(Beware: Usual monologue of epic proportions that really isn't anything but me pontificating about my personal point of view)
Personally, I'd say no, that any show that was appopriate for kids that young wouldn't have excessive amounts of gore to begin with and we tend to sugar-coat everything for kids today and round all the edges and such, which I personally think can be far more damaging in the long-run than a little trickle of blood now and then. I can remember getting so angry at my mother for not letting me watch Estiban and the Mysterious Cities of Gold on Nick Jr when I was a kid and just to spite her I'd watch it anyway when she wasn't home. Granted, I don't remember a lot about that series, but I know that it was more intense and interesting and involving than anything I'd seen previously and I was utterly in love with it. That show made a huge impression on me because it wasn't sugar-coated and round-edged like the other stuff I watched was and I was utterly in love with it.
Something I don't think most people remember is that kids don't like being talked to like they're stupid and they probably see things in real life that are way worse than anything they see on TV anymore, even things like scraped knees and broken bones. Kids are pretty savvy and while I don't think they should sit down and watch a Tarantino marathon or anything, I think they could easily handle a trickle of blood coming from someone's mouth or even a gun being pointed at someone's head (especially if the person doing the gun-pointing gets socked in the head by the hero of the show for doing so).
Come on, look at some of the violence Disney's used to off some of their villians in G-rated movies: Ursula was run-through with a broken ship… thingie, Frollo fell into a lake of molten lead, Malificent was run-through with a sword, Clayton had his neck snapped. Heck, they killed off good guys, too, Bambi's mom, Quasimodo's mother cracked her head open on stone steps, Tarzan's parents and a baby gorilla were torn apart by a jaguar, Megara was crushed under a pillar, Simba's father was run down by stampeding wildebeasts.... All these movies got G-ratings but there's no WAY they could get away with this stuff on TV shows, and it's definitely far worse than the stuff they've been editing out of 4Kids. That doesn't make any sense to me.
Regardless of all that, I know that kids are impressionable, but I don't think they're nearly as fragile as we tend to think of them being. Like Solar Knight said, is it really more responsible to show people being punched around and fighting with each other without getting hurt, or is it better to round all the edges and let them think they're indestructable? I mean, millions of kids grew up reading Superman but how many of them tried to bounce a bullet off their chest? That seems to me that it's more the responsibility of the parents to equate their kids with consequences than the responsibility of the TV to be a babysitter. But that's me.
--Bevin