It can wrap around to extremes sometimes, too.
I'm also sometimes surprised by how effectively a simple statement like "I don't want to spend money on that" can shut down even a pushy salesman. Or even the simple "No." can work wonders.
I've never seen any comments regarding a single period, but I've seen comments (and sometimes agree with them) regarding the perceived rudeness when ending messages in ellipses.
"Good job..." seems almost sarcastic compared to "Good job.".
Edit: Reading your link: First, that's well-written and insightful; thank you.
However, it seems like a common (young, if I dare guess) frustration with human communication, especially among geeks (if I dare guess, here on HN, and including myself as one): Communication is not transmission of information, but a social interaction. You have to think about all these other things (where many geeks feel out of their depth), and in fact those other things are more consequential than the information (with which many geeks feel very confident). In other words, it sucks to have all the information, to be a master at it, and find that it doesn't matter so much.
Tip: Don't try to dismiss it; it's human nature and won't change; learn the skills. 'Skill' #1: learn to not objectify the other party (they aren't an endpoint device in your communication network), and the best tools for that: curiosity about them - about their unique universe in their mind, their own wants and perspectives, completely unrelated to yours - and compassion: they have a difficult life too. (Of course, that's just my perspective! :) )
I think this can be said of the British too. Though we would probably make the mistake of interpreting it as rude rather than aggressive. As someone who doesn't communicate particularly directly, I often make this mistake myself.
Though I'm not sure which side of "the pond" is worse in this respect.
Especially when discussing politics it can be confusing as hell trying to figure out what somebody really believes/wants because the tip toeing around egg shells can make the words impossible to decode.