Very good point. Significant numbers of users, especially over time, would less likely know about the telemetry and to the extent of the data collection. Opt-in (with obvious notice) is clear consent. Opt-out "consent" after the fact, which is made less obvious and after who knows how much was taken, not so much.
In the proposal and blog posts, they estimate that an installation will send on average ~1 report per year, with the expectation that this will decrease over time. They are very open about what information they are and are not collecting. Additionally, they will be making the raw data collected publicly available, so we can all inspect it to see.
I'd be curious to know if another tool which collects metrics is as transparent as the Go team.
