Sorry MicroDrie, I do not quite agree. While most PC and Mac users have at least a faint idea about the directory structure of their computer(s) and where they should put files like documents etc, this is certainly not the case with most smart phone and tablet users. Apart from a few developers and freaks, no normal samrt phone user has a clue where Android or IOS stores its bits. The OS's do not advertise their data and program structure and omit on purpose something like a file explorer that could provide insight.
Thus, it is asked too much of a normal user to select the directory where backups should be stored. I just picked download and document directories as examples, because they sound at least familiar to a Windows user. Therefore, it is up to the developer to define where to store necessary files for backup or transfer and not to the user, because he/she just simply does not know or care about the internals of his phone. But sadly, Android does not allow this anymore.
Anyway, thank you for your input and have a nice weekend, Georg