Well, there's a new trend sadly emerging on the Nexus apparently. When modders publishing their work on the Nexus want to be granted permission for things like using music from Fallout 3 or meshes from Skyrim into a Fallout 4 mod the answer is "no". While I can understand when a company says no to their assets being used in games developed by other companies and having no relation whatsoever with the Fallout franchise, I hardly see the relevance of the rule when it is about using assets from a previous game in the same series which was furthermore developed and published by the same company. As for using meshes from Skyrim? Come on, it's still a Bethesda game so what's the point to forbid that? Unless...
Could it be that people working for the Creation Club do not encounter the same walls?

Well, considering that the situation is getting worse NOW, it's the first thing that comes to mind for most people.