I've noticed that when friends get faster internet access (100/10 or even 100/100) they tend to download less and less, and just stream the shows/movies they want to watch. For them loads of storage is not really necessary.
Of course you still have the odd one who wants to download everything in 1080p x/h264 rips at 8-20 GB a piece.
So, for people with slower speeds I can see they'd want to have more storage, as streaming is not an option. (no one rents discs anymore, there's a reason the shops are closing)
Also, for the technical side, how do you back up 10TB (or more)? I suppose it would be necessary to have 2 HDDs in RAID1 with ZFS on top or something, to prevent the effects bit rot etc.