Regarding the "good intentions" change, the explanation in the linked twitter thread makes sense to me: in some contexts, assuming good intentions is a way of excusing bad behavior.
It's hard to agree on the exact boundary between enabling a jerk and making an issue out of nothing. But the old "assume good intentions" policy does sound to me uncomfortably similar to "if you're offended it's your own fault". Which is generally how people treat victims of harassment in communities where that sort of harassment is tolerated.
That is misunderstanding of the principle. Of course you still need to use your head. For a community to be welcoming for people that aren't too extroverted, not fitting anyone on that mailing list really, your approach is very counter productive if you really want to empower voices that normally don't speak up.
It is also required for completely dry technical discussions. I am not sure I would want that in open source communities though, but that is certainly a preference.
I don't know. Assuming good intentions is an advice for you, so you don't get offended. And assuming good intentions doesn't justify the impact. Even if you assume good intentions of a driver, if he drove badly and did some damage he is still responsible for the damage. Assuming hus good intentions doesn't change anything. Skill, following the rules and effect are what matters when it comes to judging.
Next time you get in a car accident maybe the police should throw you in jail for wilful destruction of property. It doesn't matter if you did not intend to damage the other car since intentions don't matter. You did the crime you should do the time.
It's hard to agree on the exact boundary between enabling a jerk and making an issue out of nothing. But the old "assume good intentions" policy does sound to me uncomfortably similar to "if you're offended it's your own fault". Which is generally how people treat victims of harassment in communities where that sort of harassment is tolerated.