The Death Culture in Japanese Animation

The two animations you mentioned are Miyazaki Hayao's animations.

The main audience of his animation is young people, so his animation will only be like this. If he becomes a demon after death, he will shed some sticky liquid, squirm like a maggot, be disgusting, or melt when he dies (not a bloody death scene). This is to adapt to the easy acceptance of people of these ages and has nothing to do with Japanese culture.

In fact, apart from Miyazaki Hayao's animation, most Japanese animations are set to be similar to people or close to the devil's image in the West, and many animations are willing to create images (Miyazaki Hayao's animation is one of them).