I think the target audience is younger males in Japan, everything the shows do relate to that audience.
Perfect women and characters they can more easily relate to (or imagine themselves being [lighter skin]) = more people watching. Plot changes quickly because they need to keep people with short attention spans entertained? The eyes (I think) are a form of pedomorphisis (look how Mickey Mouse turned from a rat like guy to a rounded baby-faced mouse), people think those things are cute.
