It would be an easy but valuable addition to be able to group layers in InDesign like we can do in Photoshop. That would allow various "versions" of a document to be turned off an on, as well as organizing more complex documents. We can group paragraph styles and swatches – why not layers? Palette items should be groupable across the board, for a consistent interface.
And there is already an app that lets you do this, but this should be included with InDesign.