See my edit.
Once again, you're being blind.
I've justified in every single one of my posts why Microsoft won't make PC cross-play a subscription-based model. There is no "fair" or "unfair"; looking at the facts, Microsoft will not be able to successfully sell Xbox Live Gold on the PC so they won't even bother.
Microsoft needs people to update to Windows 10. They're going to do it by giving gamers reasons why Windows 10 is a good gaming OS; keeping multiplayer free is a good start. Otherwise, why would they promote PC? People could use the PC to figure out how Xbox Live auth works, and crack it. If they wanted us to pay, they'd convince to purchase an Xbox One.