I checked that link and they call it "server-side encryption" -- do they mean encryption at rest? If so, it seems terrible that they would allow data to live unencrypted on their non-volatile storage, why do they even give the customer that option?
Other than for very specific kinds of customers that want to supply their own encryption keys, why should it even be their concern? The whole point of cloud is to take the hardware away. Encryption is cheap, just do it.