Based on the explanation given, there's absolutely no privacy benefit to not including this code. The fact that it's Terraform doing the work is already being sent via the User Agent in the API requests. The fact that it's _you_ who is making the API calls is also embedded in the request. This amounts to a minor hack of Azure's API logging to enable slightly more convenient reporting. It sends no new data. In other words "opting in" or "opting out" has zero impact on whatever privacy implications you are worried about. This comes down to a simple misunderstanding of what's going on.

Most people wouldn't care about it's usage and will keep it as the default.

i dont know why this is getting downvoted