I work at Mozilla, but I'm speaking for myself here, and not on behalf of Mozilla as a whole.
For those interested in understand more about this project and why we're doing it, here you can find an introduction of Differential Privacy and what we're trying to do. https://twitter.com/Alexrs95/status/896366072240144385
1. You will absolutely obliterate any trust you have with actions like this. This is important. Because if you continue to ignore this and you will have tons of data but you will be absolutely clueless as to why your product and brand are completely abandoned.
2. This data isn't worth that much to begin with. Here is a crazy idea, try to make a better browser instead.
This data will be used in the pursuit of #2. As it turns out, a lack of understanding of what users are doing with their browsers is an obstacle to making a better browser. Performance issues in complex systems often only show up in production, and that's what Mozilla is trying to collect this data to fix.
As a user, I don't want to waste my time learning up on Differential Privacy. Am I really expected to read up on it and prove to myself that the theories work and are safe to use? Why should I take the risk that the mechanism might leak data? The only sensible secure choice is to not allow it. Let users opt-in, don't force them to opt-out.
