It absolutely amazes me that there are so many anti-consumer people here.
Apple is not a SaaS, IaaS, or PaaS. They produce tangible goods that consumers own. Outside of violating state or federal laws, including the Computer Fraud and Abuse Act, you are legally entitled to do whatever you so choose with your property.
Why is everyone okay with Apple dictating what you can or can't do with your property? You paid for it, and not just for a license. It is YOURS, why are you giving up your rights?
If Microsoft only allowed you to sync one Email account in Windows, would you still go "well, I don't know why you'd need multiple accounts, you're stupid if you do".
Does everyone here tell their customers "tough luck, I guess try to get around that "feature"'?
The only reason apple does this is because they sell music. If they didn't, there would be absolutely no incentive to put these types of constraint on a consumer device.