And this is an area that Windows wins at. In Windows 8 on my tablet, it shows a Mobile Broadband connection. All the Windows Update, Outlook application, etc are aware of this - Outlook says "You may be on a metered connection" and prompts for desired behavior.
On my laptop, I can even flag a given Wireless (or indeed any) connection as metered and get the same result.
I think it makes sense that Apple is not very interested in making new features for OS X. They make only a tiny fraction of their profits from it and Mac sales have been down close to 20% from last year. To use Jobs' post-PC analogy, Why invest in making better trucks if you think the world is moving towards cars?
Meanwhile, Windows is Microsoft's bread and butter.
I'd argue that Office is Microsoft's bread and butter. Check the Operating Income figures from the last quarter -- $3.565B for Office compared to $3.296B for Windows:
Yet, they produced the Macbook Air, when they were actively working on the iPad, and the world was moving towards mobile. Also your argument that Apple is not very interested in making features for OS X falls when they announced last year that they will move the yearly release cycles.
On my laptop, I can even flag a given Wireless (or indeed any) connection as metered and get the same result.