No build step should be the future of web development. The more steps that are added that require yet more tools to learn and more dependencies to maintain, the less inclusive and creative the web becomes. Hopefully we will one day be able to look back on this time period as an evil necessity.. I mean writing es6 and building to es5 is way better a lot of the time from a development perspective but on the face of it, its absurd and its why tooling gives people fatigue and turns away new promising developers for better programming languages.
I would definitely provide a way to download the css without npm first. Like big worm said, its about principalities.