You're right. It limits, but not stops, updates on metered connections. Say you have a device that is on metered only for weeks or months, Windows will rightfully start downloading updates as not having these updates is a security risk. I think MS has made a lot of controversial decisions with Windows 10 but I don't believe consumers should have the ability to dismiss security updates out of convenience. The risk to themselves and the larger internet is far too great.

Also, putting aside the politics of telemetry data, the actual file is a compressed XML file. I don't know the real size off hand, but its just compressed text. Its not going to affect your metered connections quota. A 20kb transfer every month shouldn't bankrupt your connection.

Not to mention, its trivial to disable telemetry if you have basic technical chops. Windows updates too. Or don't use Windows if your use case is so far from the norm. Its designed for the lowest common denominator, not for techies.