I just don't think that's an accurate picture. They aren't recording your voice and storing it somewhere. Browsing and search history are collected by other platforms for predictive browse ahead and autocomplete, and it's a useful feature. App usage is collected for diagnostic purposes.
You don't have to use a MS account. You can use a local account. 10 is different from windows 8 in that regard. You can take Cortana off the taskbar. Use a different browser in incognito mode all the time. Store your encryption keys in a TPM, smartcard, or Active Directory. There are actually lots of options. You have to actually look into it though.
