I can do a quick summary of what's being proposed and why. I work in the JS team at Mozilla and deal directly with the problems caused by insufficient data. Please note that I'm speaking for myself here, and not on behalf of Mozilla as a whole. Tracking down regressions, crashes, and perf issues without good telemetry about how often it's happening and in what context. Issues that might have otherwise taken a few day…
If user privacy is paramount, then there are multiple ways to lower the privacy incursion that is caused by the data collection. Only collect top-level domains of Alexa rank 1k. That users are using a highway is less sensitive than a specific street where there only exists 5 homes, and it reassures users that private domain names won't be leaked. Send the data through Tor. That way you only get the data about the bro…
EDIT: It should also be completely disabled in Private Browsing mode -- otherwise the optics are even worse than they are now.