Cool
. You have a very specific workflow of a staging library and presumably not ever touching the book when it is in your final library. However for many people books in their "final library" will never be in a "don't ever touch it again" state in terms of metadata. It may be they find they have catalogued a book incorrectly, have a typo in the title, change their author naming scheme, get fresh metadata based on a new metadata source plugin being available, decide to add a better cover etc etc. In all these cases the metadata is not going to be updated in their book format stored within the library without further actions. So if they are like you in being "bothered" by it then they are going to have to keep adding extra steps to their workflow to be able to sleep at night
You have agreed to de-emphasize it which is the main point - let Calibre do what it is good at in terms of managing the metadata itself in its database/opf file, and only "worry" about metadata in the book at the point you export from Calibre to a device or software that depends upon it, where plugboards can help get this the way you want it.