Someone should write a detailed history of effective altruism

You should definitely prioritize it! What about creating an open source wiki of sorts to crowd source information?

You could always double check / get citations later on.

I don't know that I'm the kind of person OP is thinking of, but beyond opportunity cost there's also a question of reportorial distance/objectivity. I've thought a lot about whether to do a project like this and one sticking point is (a) I identify as an EA (b) I donate to GiveWell and signed the GWWC pledge (c) many of my friends are EAs, so I'm not sure any book I produce would be perceived as having sufficient credibility among non-EA readers.

I wonder whether Larissa MacFarquhar would be interested? She wrote about the early EA community in her 2015 book Strangers Drowning (chapters "At Once Rational and Ardent" and "From the Point of View of the Universe") and also wrote a 2011 profile of Derek Parfit.

A possible middle ground is to make efforts to ensure that important source material was preserved, to keep option value of doing this project later. That would presumably require significantly fewer resources, and wouldn't require opportunity costs from "the sort of person who could do [the writing of a book] well."

I think opportunity cost is well worth mentioning, but I don't know that I think it's as high as you believe it to be.

Choosing someone who has been around a while is optional.  The value of having an experienced community member do it is built-in trust, access, and understanding.  The costs are the writer's time (though that cost is decreasing as more people start writing about EA professionally) and the time of those being interviewed.  I would also note that while there's lots of work for technical people in EA, writers in the community may not have found such great opportunities for impact.

Having a relative outsider take on the project would add objectivity, as Dylan noted.  Objectivity would both improve credibility to outsiders and increase that likelihood of robust criticism being made.  I also think there are just a lot of pretty great writers in the world who might find EA interesting.  Perhaps you just get different benefits from different types of writers.

There's a cost to waiting as well.  The longer you wait, the more likely it is that important parts of the story will be forgotten or deleted.

I’ve addressed the point on costs in other commentary, so we may just disagree there!

1. I think the core idea is that the EA ethos is about constantly asking how we can do the most good and updating based on new information.  So the book would hopefully codify that spirit rather than just talk about how great we’re doing.
2. I find it easier to trust people whose motivations I understand and who have demonstrated strong character in the past.  History can give a better sense of those two things.  Reading about Julia Wise in Strangers Drowning, for example, did that for me.
3. Humans often think about things in terms of stories.  If you want someone to care about global poverty, you have a few ways of approaching it.  You could tell them how many people live in extreme poverty and that by donating to GiveDirectly they’ll get way more QALYs per dollar than they would by donating elsewhere.  You could also tell them about your path to donating, and share a story from the GiveDirectly website about how a participant benefited the money they received.  In my experience, that’s the better strategy.  And absolutely, the EA community exists to serve a purpose.  Right now I think it’s reasonably good at doing the things that I care about, so I want it to continue to exist.
4. Agreed!

I think there could be a particular audience for this book, and it likely wouldn’t be EA newbies.  The project could also take on a lot of different forms, from empirical report to personal history, depending on the writer.  Hopefully the right person sees this and decides to go for it if and when it makes sense!  Regardless, your commentary is appreciated.