It’s been noted before that Windows 10 has been downloading in the background for users of Windows 7 and 8. Now it appears that the update is selected by default – allowing for accidental deployment of a massive update. The aggressive nature of the Windows 10 roll out is causing a lot of grief for users in all kinds of scenarios. It’s a large download – which would slow some networks and connections. This could also cause issues with available space on machines with little to spare (like some with smaller SSD’s). It’s a really good idea to pay attention to the optional updates on the list as you run them.
Microsoft’s quote on the matter:
As part of our effort to bring Windows 10 to existing genuine Windows 7 and Windows 8.1 customers, the Windows 10 upgrade may appear as an optional update in the Windows Update (WU) control panel. This is an intuitive and trusted place people go to find Recommended and Optional updates to Windows. In the recent Windows update, this option was checked as default; this was a mistake and we are removing the check.