Sometimes, I need to "quote" a certain icon to explain how to do something on an on-wiki feedback. Not having OOUI icons on Commons don't allow me to integrate them to conversations and in documentation. I only can upload the icons by myself and they will never be updated, or create a link, that requires an extra effort for users.
It is possible to coordinate a Git repro with Commons. Updated icons would be shared on Commons, which would update icons used on the wikis.