"or paying for the required license?"Where was the acceptance of a contract requiring that? Microsoft just gave people a free upgrade.
I imagine the definition of "upgrade" depends on the needs of the customer. The merchant of the license is inherently unable to evaluate this. Installing software without explicit consent, especially not-functionally-equivalent-software, is inherently wrong.
It's amazing to me that we're all so chill about a company in Redmond having root access to our PCs because they pinky-swear they will never misuse it.