I vaguely recall Visual Studio has this option where you can generate some sort of class diagram. It looked like shit the last time I used it (~2019) especially as your classes get more and more functions built into it. I also can't imagine how shitty it looks for codebases that have a significant coupling problem.
Furthermore, creating a UML diagram is a documentation process rather than something that should be automatically built in. I put it on the same level as writing a document in a word doc or something that's done as the project gets closer to being finished. Some places can live with it, a lot of places (actual software companies) probably do not as they move unreasonably fast (Agile) which does not even allow time for documentation or they just purposely neglect documentation.
> Why aren't code visualization tools more popular? The options out there seem outdated
Because they look like shit. I tried mermaid with markdown, I was not happy with the results, I tried plantUML back in 2019, I hated how it ended up looking, I hated how I have to install java for it, and I gave up on it pretty quickly.
The only code visualization tool I ever use is either draw.io or MS Visio. At lease there's a plugin for that for VS Code.
> Would you want to use these tools? What would be your ideal tool?
Markdown with vim option. It also must have an option to force a top-down flow approach and not freaking forcing it to be a left-right layout