There are many problems here.

At the end of paragraph 2 and the other examples, you say

This exactly mirrors the Prisoner's Dilemma.

But it doesn't, as you point out later in the post, because the payoff matrix isn't D-C > C-C > D-D, as you explain, but rather C-C > D-C > C-D, because of reputational effects, which is not a prisoner's dilemma. "Prisoner's dilemma" is a very specific term, and you are inflating it.

evolution is also strongly motivated [...] evolution will certainly take note.

I doubt that quite strongly!

The evolutionarily dominant strategy is commonly called “Tit-for-tat” - basically, cooperate if and only if you expect your opponent to do so.

That is not tit-for-tat! Tit-for-tat is start with cooperate and then parrot the opponent's previous move. It does not do what it "expects" the opponent to do. Furthermore, if you categorically expect your opponent to cooperate, you should defect (just like you should if you expect him to defect). You only cooperate if you expect your opponent to cooperate if he expects you to cooperate ad nauseum.

This so-called "superrationality” appears even more [...]

That is not superrationality! Superrationality achieves cooperation by reasoning that you and your opponent will get the same result for the same reasons, so you should cooperate in order to logically bind your result to C-C (since C-C and D-D are the only two options). What is with all this misuse of terminology? You write like the agents in the examples of this game are using causal decision theory (which defects all the time no matter what) and then bring up elements that cannot possibly be implemented in causal decision theory, and it grinds my gears!

And if two people with these sorts of emotional hangups play the Prisoner's Dilemma together, they'll end up cooperating on all hundred crimes, getting out of jail in a mere century and leaving rational utility maximizers to sit back and wonder how they did it.

This is in direct violation of one of the themes of Less Wrong. If "rational expected utility maximizers" are doing worse than "irrational emotional hangups", then you're using a wrong definition of "rational". You do this throughout the post, and it's especially jarring because you are or were one of the best writers for this website.

playing as a "rational economic agent" gets you a bad result

9_9

[...] anger makes us irrational. But this is the good kind of irrationality [...]

"The good kind of irrationality" is like "the good kind of bad thing". An oxymoron, by definition.

[...] if we're playing an Ultimatum Game against a human, and that human precommits to rejecting any offer less than 50-50, we're much more likely to believe her than if we were playing against a rational utility-maximizing agent

Bullshit. A rational agent is going to do what works. We know this because we stipulated that it was rational. If you mean to say a "stupid number crunching robot that misses obvious details like how to play ultimatum games" then sure it might do as you describe. But don't call it "rational".

It is distasteful and a little bit contradictory to the spirit of rationality to believe it should lose out so badly to simple emotion, and the problem might be correctable.

You think?

Downvoted.