"I did it because I was angry" is still a more accurate explanation of cause and effect than "I did it because X is an idiot and deserved it" or "I did it because it's obvious that was what I should do, anyone could see that." You're right that "I did it partially because I was angry, were I not angry, I wouldn't have done it" is an even better illustration of cause and effect, but I was using the example to refer to more naive people who aren't very introspective, but who can't avoid doing it a bit.