That's not a side effect but rather the point, isn't it? To allow others to communicate to you more directly by committing to not responding emotionally.
Edit: to be perfectly clear, by "not responding emotionally" I mean not sending a nasty email while angry. I don't mean suppressing any emotional response.
Well, one criticism of Postel's principle is that it's contributed to the security hazards of the modern-day Internet. We have a lot of ill-behaved software, written by programmers who felt free to take the easy way out because everyone else bent over backwards to accommodate them. The critics argue that a more formal, RFC-respectful approach -- the equivalent of what we'd call "political correctness" in a conversational context -- would bring about a safer Internet (or safer world) for everyone.
I don't subscribe to that point of view because I disagree with the idea that safety and security should be prioritized above virtually everything else including freedom. But I think it's worth acknowledging in a devil's-advocate sense. The question, "What's the minimum level of standards enforcement / political correctness that's required to enable technological development / human progress?" is an interesting one. Clearly the answer isn't "Zero" in either case.
Political correctness is about being conservative in what you say. Crocker's rules is about being liberal in what you accept. You could do both, then you'd be following a conversational equivalent of Postel's principle.
