No, we are not limiting the input to the visuals (and that's not what I said). Look, if you want to do a deep dive into the movie, that's fine. But you would need to understand a little more about it. For example, despite the oft-repeated line that he never read the book, that's not true. That's not even how things work. Instead, he read the original script by Neumeier. Neumeier (also the original writer of Robocop) was a fan of Heinlein's book, and the original script was more "on point" so to speak. Verhoeven then went to read the book, which he couldn't finish (only getting through "two or so chapters" according to an interview that took place more than 15 years later, but we all know Verhoeven is notoriously unreliable about his process) because he didn't like the right-wing militarism.
So he engaged in a collaborative process with the scriptwriter (who was intimately familiar with the source material) to change it to suit his vision.
Anyway, I don't find this conversation very productive- things that are completely obvious to some, aren't to others.* For that matter, the fact that the topics Verhoeven was covering become more relevant after the movie was made is more a testament to what it was doing right than anything it was doing wrong.
If you liked the source material, good for you. A movie is not the same as the book, and for many people (including me), the movie is a much better work than the book ever was. Once you peel away "oh, but it introduced power-armor" you are left with little more than a thinly-veiled polemic against the nascent anti-nuclear movement, tinged with the least-appealing aspects of Heinlein's ... we'll say unique political philosophy.
*At a certain point, I expect people to say, "C'mon, that thing is about people eating babies. How could anyone call it satire? Sheesh. Modest proposal, I don't think so!"