[neodymiumphish]

To be fair, they aren't (at least not yet). You can still set up a local account.

As for why/whether Microsoft should decide that, it's kinda their call. Plenty of other apps/services/devices require an account of some type. (effectively) All require agreement with their terms of service.

By your logic, why aren't you irritated that Microsoft requires any type of account at all for Windows (same for any other OS)?