I don't think we really need most of this part. Focused son-generic (ie: Non-Wikipedia-like) skins should not be packaged with the tarball. There are many different categories of focused skins and they will all be useful to only some groups of wikis. So we shouldn't be packaging things not generically useful into the tarball. Those skins should all be installed normally.
Btw, we also don't need to try including so many skins by default. Even WordPress — what appears to be the aim of a lot of these paragraphs – only bundles one single skin. So MonoBook/Vector/Modern are quite enough for the standard tarball.