Of course, I'm not suggesting you do proper marketing with those in-dev screenshots. Please don'tA screenshot can barely tell you how the UI really works, you'd need a series of them, much less inform you about gameplay. Also the game is using the "dev ui" right now. Fancy UI features and UI theming will come at the end once it is settled.
But for "dev log/blog" style updates, screenshots still provide a lot more clarity and context than text alone could (if there is a screenshot that does apply, of course, sometimes there just isn't, especially for simulation heavy games).
It's hard to imagine the "big picture" for anyone not entirely familiar with a project if all you have is walls of text.
Information-parsing wise, generally people cling to headlines/highlighted "titles" and images first and if those pique interest, the rest of the text is parsed.
I assume the goal with dev blog updates is have something for interested people to keep the interest up (for which some more visuals at least wouldn't do harm) and lure a few more in along the way (for which the lack of visuals most likely does harm).
One thing I have developed a habit of doing while developing is to take screenshots if anything strikes me as "this might be worth mentioning somewhere" - even if it's just a hilarious bug.
That way, when I do write an update (or just present during a meeting) I'll have something more than just me talking.
The context for me isn't game dev, but still development with visuals.
And as a bonus, looking at years-old "screenshots" of stuff can be pretty funny