We now know the tradeoff for free Windows 10: Microsoft wants data about what you do with your device. But you don't have to send everything you do back to Redmond.
You can control the data you send back, and how often, by delving into Windows 10's privacy settings (we've taken you here before) and looking specifically at Feedback frequency and Diagnostic and usage data. The former is typically just an automated survey, but the diagnostic component actually peers into your machine.
These features comprised the Customer Experience Improvement Program, or CEIP, in previous versions of Windows—and they were voluntary. In Windows 10 they've become mandatory, but you can control some aspects.