It's on by default so that users will interact with it and try it out. This is pretty standard practice on every major OS or application you use today. New features are enabled by default and the user gets to figure out how to disable them if they don't like it.
Case in point, the latest update to Gmail on Android enables a feature of opening URLs in a Chrome Frame inside Gmail instead of using your browser. This is great for Google, not so much for the user. I got screwed over because of this feature because a nonce token I received was consumed by the Chrome Frame which promptly crashed.
Windows 10's suggestions and prompts are about on par with MacOS High Sierra's. If you're questioning that statement, try not setting up iCloud some time then come back to me.