Why won't messaging apps let me save content easily?
Taking example of Signal, I need to save each and every image manually to be me available outside its sandbox. Why is it like that rather than making it easy for me to use things that have been explicitly sent to me?
I have used another messaging app called Twin Me which also does something similar.
I always used WhatsApp earlier that allowed me access to the media downloaded in chats and let me take local backups but unfortunately they now allow only Google backups!
Assuming you're on Android, this is coming from the OS. It's still possible to save data in an externally-accessible place, but the default is storing things privately for each app. It's annoying for use cases like yours, but it's arguably better for overall security.
It's not a matter of freedom, it's a question of desired functionality. If anything, keeping your data in a sandboxed area by default respects your freedom more (that is, freedom from other apps scraping your data).
If it's on Github, you could file a feature request to have that default behavior changed.
The reason Signal does this is that they consider your deivce storage 'unsafe', as it can be more easily accessible by other apps. AFAIK not providing the option to let you do it anyway is purely because the Signal devs don't want to.
Threema for example has an option to save all received media to normal storage, similar to WhatsApp.
Suppose I want to keep a backup and decide later what I want to discard, I will have to keep on doing it manually each time to update the archive.
WhatsApp did it properly before where I could easily backup the whole directory which included all media and chat database locally. But now they are forcing Google backups which I do not like. I was looking for alternatives but they all seem to need this kind of manual saves. Eg. Signal, Twin Me, and the recently tried Jami.