I found @soatok's argument for E2EE encryption in this post quite interesting:

End-to-end encryption doesn’t just protect the users, it protects the people operating the infrastructure. And that’s why it still matters.

That's pretty much the only reason why http://mega.io/ is end-to-end encrypted: the previous Kim Dotcom project - Megaupload - was seized by FBI and hadn't E2E, making it a easy target. MEGA's encryption isn't good (source: me) but it's good enough to avoid making them an easy target for law enforcement.