this is a HUGE deal when you have a backup disk that you manually update... especially when you have nested folders and you save files to several different folders.
That they took this out is a testament to the dumbing down of the OS in a (pathetic in my mind) attempt to make windows look more snappy.
Fine to leave it off by default, just have a toggle button to activate folder sizes in explorer... and then have that toggle button "invisible" by default (only to be made visible by navigation to a buried settings menu). That would protect the Microsoft desire to make the computer look snappy when exploring for the uninformed and it would enable the educated user to control his/her computer as he/she sees fit.
Question - why are you manually updating your backup disk? You can save yourself a LOT of time by either using one of the many software options or by writing a script to handle and manage your backups for you. I used to have a script that would create a rolling weekly archive for all of my important documents. I may not be understanding your scenario properly, but it sounds like you're putting more effort into this than you need to.
Folders are just containers (specifically, they're delimited file paths). Folders do not have a size. The sum of the size of all the files within the folder determines the "Folder Size". If you've got a folder that contains several hundred files and two files have changed in filesize, but the sum total is the same, how do you tell the difference based on "folder size" alone? Your
files contain the data. Make sure you're backing up the proper versions of the files and the folders themselves become meaningless (as long as your backup solution preserves relative file paths).
Or you could just use git. :awe: