Point taken. And for the record on the whole I side with Apple.It's not really about the technical details. It's about Apple's intention. The current cloud system was never designed to prevent Apple from accessing the data. They never promised their users otherwise. They did, however, promise that they wouldn't be able to access data on devices without the user's consent. And now they are being asked to dismantle some of the mechanisms they implemented to fulfill this promise. It's essentially as if the government demanded from a safe manufacturer, whose business depends on making secure safes, to use weaker locks so the safes can be cracked more easily.
But I don't think they should be decrypting iCloud backups. While as you say they never promised they wouldn't, the average user does not appreciate the divide between local and server and would expect Apple to take the same approach with both. The user is not informed that by using iCloud backup Apple and the government could access your data. Rather, they advertise its encryption so heavily that I would argue the user would expect the backup to be impenetrable.