Npm already does it at the package registry with ignore/npmignore files, and that's the package authors choice. How much storage can you really save? 50MB? 200MB? is it really worth the risk of running rm on some glob pattern and cross your fingers the packages don't require any of the deleted files?
I tested it recently on a clean install of Strapi: about 250 MB are freed up. Storage is cheap but that still represents a lot, especially inside a Docker image.
The patterns used to find files are specific enough to target only those files that are well known to be useless at runtime.
You are taking a big risk of subtle breakage right now, and a big risk of breakage as you change your project code in the future, as you may start to invoke a code path that needs that resource in the future.