Earlier quoted context omitted.
I'm a professor currently writing an online textbook. I can assure you that writing a textbook, without anything interactive, is extremely challenging. I find it hard to imagine a time when my book will be good enough that adding interactive explorables will be the best educational return on time invested. (Though I'm thinking about it!)
Not to dismiss your work, but do you think the best investment of your time is to write another textbook (assuming this is an undergraduate level book in a relatively well-explored field), or in adding detail/great illustrations/great interactive charts to an existing work? I know (really, like, I know ) how detrimental this would be to anyone's career, and I'm not saying this as a moral condemnation of what you're d…
For your broader question---I understand what you're saying, but it's very difficult to edit someone else's writing. That's where "committee voice" comes from: it's the lowest common denominator to multiple authors working together. And often how I visualize things comes from how I look at things, and coming up with a visualization for how someone else looks at things is hard.
Take the OP as an example. This is a long blog post on gears in general, but animated by the specific question "what shape are gear teeth". If I were writing a blog post about gears, I wouldn't start at that place. And then, imagine if this blog post started text-only instead of visual. "Involute" would now be described with algebra, not a picture. The algebra is complex (compare the Wiki at https://en.wikipedia.org/wiki/Involute), and that algebra itself would need pictures. Illustrations and explorables aren't, ideally, something you sprinkle onto existing text.