I would really like to see a mode in LibreOffice that blocks all the external resources (images etc.) from loading into the document. Allowing such resources to load by default poses a threat to privacy and can be used to track people. The problem and method of exploiting this is described (in Polish) in this article: Śledzenie otwierania dokumentów MS Office (it mentions LibreOffice specifically).
File an enhancement request at bugzilla: https://bugs.documentfoundation.org//