Microsoft has certainly done a fair bit to encourage taking the free upgrade to Windows 10 for those on Windows 7 and 8, with the last tally showing 110 million PCs are now running the OS. However, it looks like the company has pushed the encouragement a little too far, with users reporting that the optional update is being automatically "checked" in Windows Update, prompting an install for users who aren't diligently checking the "Optional" tab before initiating a round of updates.
Speaking to Ars Technica on the matter, however, Microsoft says this was a mistake and they are removing the automatic check:
"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."
While the automatic check on an optional update seems worrisome at first, keep in mind that the process still requires a fair amount of user input to go forward. While the checkbox shouldn't have gotten an automatic tick in the first place, anyone who found themselves in the middle of a Windows 10 install would have ample opportunity to back out.
Source: Ars Technica