Smartphones shouldn't silently send private data into the cloud without asking the user first.
I for one would rather back up the data to my own server or locally instead.
I agree. Now, would you pay for that option? How would it be developed? This is the critical problem.
You could implement Android's storage app framework API around git running on each of your devices, and peering to your own servers (and other devices). This would give you at least a Dropbox style system that works, but the rewards for the (not that large, but non-trivial) investment needed to do it are non-existent.
