The use case is this: I'm building a product configurator. When parts of the product are clicked, the color selection area for that part is made visible. In some cases multiple "parts" should cause the same color selection area to be made visible. For example I have a helmet shell with a logo on it. The color of the logo is dependent on the color of the shell. When the logo is clicked, the color selection area for the shell should be made visible.
Currently I'm doing this by using the id of the logo to trigger the shell selection area to appear. That means that I have to have multiple separate parts with the same id.
I would prefer to have arbitrary data (like selection_area=shell) associated with the part, so that my code can fetch the data and select the correct selection area.
I can imagine allowing arbitrary data to be associated with nodes could have many other use cases as well.