People make verbose and lengthy comments instead of short and simple ones. People always speak in a certain type of tone, signalling that they are smart but also that they are Reasonable and they are listening to the points of their opponents. People lace their comments with subtle disclaimers and possible lines of retreat. People take care to use an apologetic tone.
I'm not sure what the problem with any of these is.
In other words, what you call wasteful signaling, I'd call good rationality habits (or even good social skills). You say
Individual people (no, no one specific) just need to relax and to be less personally involved in the site or in the things they say and the arguments that they make.
But it's exactly things like leaving lines of retreat and using a polite tone that allows them to be less personally involved and not get caught up in things like having to "defeat" their "opponent".
1 Length is only good insofar as it adds to meaning. Most length on LessWrong doesn't do that. For example, I can summarize your first point as:
Long comments make arguments clearer and make communication faster. Good communication is good, within certain limits, and I think most comments fall within those limits.
I don't think any important information is lost there. I disagree with your assessment of communication practices on LessWrong.
2 I don't think we should react to differences in tone the way that we do. The fact that our community has different ...
Today we're announcing a partnership with Castify to bring you Less Wrong content in audio form. Castify gets blog content read by professional readers and delivers it to their subscribers as a podcast so that you can listen to Less Wrong on the go. The founders of Castify are big fans of Less Wrong so they're rolling out their beta with some of our content.
To see how many people will use this, we're having the entire Mysterious Answers to Mysterious Questions core sequence read and recorded. We thought listening to it would be a great way for new readers to get caught up and for others to check out the quality of Castify's work. We will be adding more Less Wrong content based on community feedback, so let us know which content you'd like to see more of in the comments.