Their most basic principle, "the user decides", had been stated here since 2014 https://github.com/gorhill/uBlock/blob/master/MANIFESTO.md

Well, it could be opt-in and disabled by default.

This does sound like “the user decide” indeed. The issue is: allowing that will likely be popular among people who should know better (like me) and it puts uBO into a position to be able to do some shady things that are hard to prove.

They’ve been in that situation before, with the original uBlock, and they’ve learned not to trust their own team.

Tech savvy developers could opt in to send their data and only do so from a controlled environment. If they notice a site misbehaving, open up an incognito window, go into "call home" mode and start collecting useful info. Sure, it's not for "regular people" but this type of reporting never will be if you also want to respect the integrity of your users.

Taking care of a server that receives browsing data from lots of users in lots of countries must be a nightmare.