If you accept the "rationality is winning" definition, it makes little sense to come up with downsides about rationality, that's what I was trying to point out.
A wrong way to put it. If a decision is optimal, there still remain specific arguments for why it shouldn't be taken. Optimality is estimated overall, not for any singled out argument, that can therefore individually lose. See "policy debates shouldn't appear one-sided".
If, all else equal, it's possible to amend a downside, then it's a bad idea to keep it. But tradeoffs are present in any complicated decision, there will be specialized heuristics that disapprove of a plan, even if overall it's optimized.
In our case, we have the heuristic of "personal fun", which is distinct from overall morality. If you're optimizing morality, you should expect personal fun to remain suboptimal, even if just a little bit.
(Yet another question is that rationality can give independent boost to the ability to have personal fun, which can offset this effect.)
So after reading SarahC's latest post I noticed that she's gotten a lot out of rationality.
More importantly, she got different things out of it than I have.
Off the top of my head, I've learned...
Where she got...
I've only recently making a habit out of trying new things, and that's been going really well for me. Is there other low hanging fruit that I'm missing?
What cool/important/useful things has rationality gotten you?