Writing down the simple stuff can be nice if you want to:

* Stop doing stuff in that field for months and have previously processed notes to reload in your head when you come back.

* Give feedback to maintainers on what worked/what didn't when you entered their ecosystem.

* Communicate to newbies how you overcome X problem when learning Y. Not everyone may have your particular insight. You could roll it into a blog post or other communications.

* Provide stepping stones for you to relate other frameworks and languages back to what you've already seen and know, to solve challenges in different domains.

I find that most more specific ideas for using the data come at random periods throughout my life. The questions are usually non-obvious when just staring at the data. I write them down as little notes themselves and come back to them when I have interest/motivation.