I heartily agree - those liveries are a waste of time and bandwidth during the update process, and then time-wasting when we have to delete them.
PLEASE place them as an optional inclusion in the update process, with an image or two to illustrate what they look like so that we can decide if we want them or not. This was done in a professional way with the Orbis Flying Eye Hospital DC-10, and should have been done with free liveries, as not everyone is going to want them.
Another gripe since SU5 - why can’t there be an option to roll back to the previous version of the sim in case (like this last update) things get badly broken, simply don’t work, or regular CTDs result. That may also require the option to decline mandatory updates.
Because from a technical perspective, because of the way multiplayer works (whether you use it or not), MSFS acts like an MMORPG, and therefore all servers and clients worldwide have to be on the same version. There is simply no mechanism to do what you have suggested. Please don’t eat the messenger, I’m just reporting the news, not making it lol…