Couldn't agree more, the Add to OneDrive is a terrible option and we disable it as well across every single client we support. One of the main issues is that users often have 100's of files and folders in their OneDrive folder and now a Document library link gets lost in the mix. The transition from Mapped drives to SharePoint was super easy when all your Sync'd libraries lived under one clean area that we can control from Intune. Not being able to do that will be a nightmare both for end users and IT Admins.