Regarding your thoughts, Luna is a fusion of both approaches. When you create and connect nodes, you are manipulating the program structure - you define how data flows between components. However, every node has the ability to display an interactive results visualization and input data widgets. Basically these visualizations and widgets allow you to work directly with data – you can create canvas visualization which let you paint on it, you can create a 3D scene visualization which would allow you to not only inspect 3D scenes but also modify them etc. These visualizations can be displayed below nodes or can be detached to be separate windows and are defined as HTML/js snippets.
Does it make sense to you?