You guys got to remember those are mostly written by developers. There's a bit of a chicken&egg problem: when you've been playing with software for a while, it's difficult to figure out what might be a problem for newcomers.
That said READMEs files should reflect stuff that's a good idea to do if you're using that package PREFERABLY IN A VERY TERSE MANNER. If you are using packages YOU CAN HELP. Yeah. What do you think is hard to figure out and could use a mention in a pkg-readme ? Bear in mind that we're mostly talking OpenBSD specific related stuff. But personally, I don't mind a quickstart on "unfriendly" opensource that's hard to get to work without looking at their docs. THIS IS AN OPPORTUNITY PEOPLE!!! You are using OpenBSD and you thing it's difficult to contribute ? Maybe you can share your experiences about making things work and what was hard to figure out ? (Side note: pkg land is very tricky to automate. Some of what you're going to say I'm probably already aware of, but nevertheless this might give an idea about priorities on what to work on first)
