This is completely useless because npm still downloads those files and the hdd space is pretty negligeble. It should def go under the category of troll driven development. This might be useful for docker images that will be distrubuted and will be downloaded a lot, but even there it's a stretch.

That being said, it would be great if npm had some functionality around packaging only the necessary files for actually running the module and removing all unnecessary files (tests, source code, documentation) and have an opt-in option to install those.