signofzeta said:
Because death, evil, and pollution are not good for the children, and kids don't like plain things.
Haven't you heard of the phrase "We are going to take pollution down to zero"?
Ok, if you're gonna take those types out, what happens to Gengar? Drapion? Spiritomb? I'm pretty sure none of those fit into the types you mentioned in your first post.
Also, I don't really think Ghost types inherently say they are dead beings in their Pokedex entries; think of them as more supernatural/spiritual beings. I think some of the closest things to death they mention are: stuff about stealing souls - Chandelure etc, but only in the 'Dex entries (and who reads those anyway?), and on some tv shows/films they have ghosts (see: things like Scooby Doo).
Dark types tend to be more associated with sneaky or brutal attacks/literal darkness rather than evil, see two examples: Liepard/Purrloin and Hydreigon; Liepard sneaks around, is said to vanish/reappear, and its pre-evolution (Purrloin) steals from trainers by putting on a cute act and taking their belongings whilst their (the trainers) guard is down.
Hydreigon on the other hand is said to be a brutal Pokemon who attacks without thinking towards anything.
And in children's tv there are the 'bad guys' alot; tv shows/films aimed at them have some kind of antagonist. Heck, as a child I remember watching a thing on tv/video where the main antagonist was a dog who stole sheep with the intention of turning them into dog food, and almost killed a couple of humans with said sheep, totally remorselessly. And this was aimed at a young-ish audience. Pokemon is tame by that standard.
Poison types don't inherently talk about pollution (correct if I'm wrong), even though some do imply that pollution caused them (Grimer, Trubbish), however I don't think a child playing Pokemon would be able to note that pollution caused it. It's rather the presence of venom, or having sludge/poisonous gases (see: all Bug/Poison types, Grimer, Trubbish, Gulpin, Koffing). Grass/Poison types are simply poisonous plants, and I'm pretty sure that children would probably know about things such as poisonous mushrooms.
About Normal types: I see where you're coming from about kids not liking normal things, but when you have 650+ Pokemon in a game there will be some that simply do not fit into any other type. Ok, all the Normal/Flying types could be retconned to the Wind type you had mentioned, but the whole thing about types with Pokemon is that they are different elements. The Normal type is simply a lack of elemental presence. A lot of Normal types can learn similar moves - a lot of those moves being ones of different elements. They can use attacks that are obviously something completely unrelated to their species (see: Blissey using Flamethrower). However they aren't that element at all. (again: Blissey can use Flamethrower. It clearly has no association with the Fire type except using Flamthrower/Fire Blast). They are meant to be mixed bags of Pokemon that can use many different attacks.
Also popped up after mentioning the Wind-type in the above paragraph: The Flying type is more to do with the fact that they can fly. The closest things we have to 'Wind' types are Tornadus, and.... something else maybe. It's important to realise that Flying=air, flight, wind, sky, those sorts of things in general.