There's no doubt Microsoft screwed this up for a number of reasons, including valid and important reasons some people need to stay on Windows 7. And had they not gotten into the whole telemetry mess, 90% of the people who didn't want the upgrade would've gone away.
But I understood the mindset.
My company's IT has accidentally done things like this before and even when it's on a corporate machine a popup coming up and saying "gonna restart in 5 to do updates" SUCKS while you're working.
The problem here is that in Microsoft's push to get Windows 10 onto as many machines as it can, they seem to have greatly underestimated the number of computers whose age or hardware renders them partially or completely borked by updating to Windows 10. And they seem generally unrepentant to the fact that they've strong-armed people into downloading an update that destroys their computer.
Going from "free" to "paid" will guarantee no voluntary upgrades, period. Perhaps if W10 comes bundles with new hardware (just like all Windows versions before it), then - yes, W10 will seep through, but no way in hell anyone will ever explicitly pay Microsoft to upgrade to W10. So they will have absolutely nothing to lose by extending the free offer, so it's exactly what they will do.