Six months ago I was teaching a beginning-programming course to six kids, using Snap!, so I was reading the forums. And there was a group effort to add documentation to many of the blocks that were lacking it. I haven't been back in a few months, so I don't know how that effort is progressing, but there were definitely some undocumented blocks that were getting documentation completed as I watched, and eventually added to the Git repo to land in the next release.

So it's getting better.

The other thing to remember is that the core Snap! development team is just two guys, Brian Harvey and Jens Mönig. When they're focused on things like trying to figure out how to get macros into Snap!, so that Snap! can truly be a Lisp (right now it's only most of a Lisp), they tend to leave the documentation effort to the community. If they had a larger team I might fault them for that, but with just two guys, I can't really blame them for focusing their efforts on things the community is less able to do, and leaving things the community can do up to the community.