It’s a design choice, and of course it arguable but it have it’s (good) reasons. By design choice user data of any App should be only be readable and modifiabl

It’s a design choice, and of course it arguable but it have it’s (good) reasons. By design choice user data of any App should be only be readable and modifiable by the active user. If user data is stored somewhere under home folder, this mechanism comes for free for the App developer and the OS handle it. If you want that same level of privacy in the App Bundle developers would have to handle it themselves (and well). But then what happen when you uninstall ? Either you are blocked because you can’t remove data from another user or you somehow require escalation to admin privileges to remove data of all users at once. Which might or might not make other users happy if they were unaware of the uninstall... With current data model choice (pretty much shared across all UNIX world and even Windows). If user A delete the App but user B still needed it you just have to reinstall to keep user B unharmed. Your proposal is not bad to optimize for disk space gain at removal, it just happen that (quite rightfully) OS vendors chooses to rather optimize for data persistence and security.