Any telemetry should be opt-in only. The open source community is passionately anti-spyware. I'd have to reconsider recommending WordPress to our clients and start looking at alternative platforms if WordPress core starts in with telemetry.

Without any telemetry, I'm can predict about half the talented developers who work on WordPress in their free time (i.e. those who are not on Automattic's payroll) would find something better to do with their time than help build spyware.

I disagree with Matt Mullenweg about a lot but in this case (as with his support of freedom of speech), he's right on the money.