[ulrikrasmussen]

I'm using yEd, but that likely has the same issues as you mention, being very open-ended and requiring lots of micromanagement of styles and layouts. Perhaps you are seeking a tool such as plantuml in which you specify your diagrams textually and have them rendered by a compiler. It only supports a specific set of diagram types, primarily from the UML family, but I think it's also possible to install a third party C4 style.