Is Apple failing to understand family users?
It seems iMessage is also able to send and receive messages from the child's device as if the parent had sent them.
Yes, you can go into Settings and disable what iCloud syncs. It's quite a list: Mail, Contacts, Calendar, Reminders, Safari, Notes, Passbook, PhotoStream, Documents
Your kid can actually Delete your iCloud account. The iCloud settings will not allow you to clear out the password and user id. Maybe there are other issues as well. Don't know.
You could create a new account for each kid. At a mininum, this means that you have to re-purchase all the paid apps from every account.
I think Apple really needs to offer a family or group plan. I know they want to sell more devices and copies of the same apps. I get it. However, I think it is more important for parents to have total independent control of their kid's devices.
The first company to offer this is bound to have a really interesting differentiating factor on the table, one that would appeal to a lot of people. Does the W8 phone platform offer this? If so, MS needs to let people know. It could be important to a large group of customers.
Guest users represent another important use case. If you hand someone your iPhone they have access to nearly everything past the unlock screen. With iCloud, they'd have access to everything on your iPads and iPods. If you have to lend someone your iPad you really have to trust that they are not going to go look under your skirt. A multi-user setup with centrally-managed user accounts would allow you to setup a "Guest" account with restricted access to your data and apps, etc.
Will Apple every do this?