If you care about your privacy don't upload your private data to ANY cloud service.
Even if iCloud was encrypted they still run on third party cloud providers who nobody knows what relationship they have with governments. Many types of encryption are breakable if you have effectively unlimited resources.
I've been using iPhones since the first iPhone. I don't sync any relevant stuff to iCloud. However, during previous iOS updates this sync turned itself back on multiple times (more than three times for sure).
It hasn't happened for a while but whenever there's an iOS update it's advisable to check your iCloud settings immediately afterwards and if they changed, you change them back and pray that your important data hasn't been sent to the cloud in the meantime.
Even if iCloud was encrypted they still run on third party cloud providers who nobody knows what relationship they have with governments. Many types of encryption are breakable if you have effectively unlimited resources.