Can you download 4k versions of movies anywhere? It's probably a rights issue, also the files will eat up huge amounts of storage space in no time.
I can sort of understand the rights issue (I don't agree with it though as it's once again making honest people suffer for the actions of others), but IMO storage space requirements aren't a valid reason to block downloads
It's not for Apple or anyone else to dictate how people use their storage space and not everyone is space constrained (I've got 20TB of disk storage across 3 NAS devices so it wouldn't be an issue for me)
I like to watch movies more than once and would absolutely prefer to be able to download a local copy.
Also, even though I have decent uncapped internet, I'd much prefer to download a bunch of movies overnight while my internet connection is say idle than stream at peak times and for people who are still on internet less than the 25mb minimum requirement for streaming, 4K becomes an impossible dream without being able to download beforehand