What problem does this feature solve?

Essentially it's an instruction to the vue-loader to import and use the style from the same file (recursively). The resulting value of style is {}, but it **tricks webpack into thinking the style in this file is not a side-effect.

What does the proposed API look like?

-- file: Palette.vue ---

<script>
import style from './Palette.vue?vue&type=style&index=0&module=true&lang=stylus&'

export default {
   style,
   ...
}
</script>
<style scoped lang="stylus">
...
</style>

It could be possible to append a similar import to the front of the script section automatically in the vue-loader, thereby making the style mandatory .