Earlier quoted context omitted.
I second that. It must be an opt-in feature.
I don't see why; you're tracked like this on nearly every website you visit unless you opt out. This isn't malicious.
I feel pretty safe in saying that most developers do not expect a command-line tool to phone home without saying, especially if this behavior was introduced in an update for a tool which didn't do that historically (and without any notification of the change).
Considering the popularity of this tool, it's a bit shocking that the core dev team of Homebrew didn't seem to anticipate that people would be upset by this. It really knocks my trust in and willingness to depend on this project.