One reason not to write it is that the feeling of being drowned in big problems is not a particularly good one, and possibly de-motivating

No! What is particularly demotivating for me is that I don't know what heuristics I can trust and when I am better off trusting my intuitions (e.g. Pascal's Mugging).

If someone was going to survey the rationality landscape and outline what we know and where we run into problems, it would help a lot by making people aware of the big and important problems.