Comment by npteljes

>Opt-in makes the data useless

Hardly. It just has some issues with regards to what you also pointed out, bias for one. But it still provides valuable insight into usage patterns, systemic issues, and enables tracking effects of developments over time. Correcting the bias is not a bigger task than it is now - I'm sure you already have an idea about feedback to different features according to reviews, user reports, discussions, and so on. Opt-in is the same, just much better.