I started to heavily use download to iOS for offline view function. I mostly watch series, which means a bunch of files organized in folders.
What is really needed is:
1) Download to iOS device by WHOLE FOLDERS. I mark the folders - and press download. Simple like that.
2) Of course, in downloaded files, I don't need a chaotic heap of files but rather the same FOLDERS I downloaded.
3) Also, one should be able to delete files just selecting them and pressing 'delete', same for whole folders.
All of these are so simple I am embarrassed you haven't implemented it yet.