When developing/configuring web applications it can be useful to change the ID of a layer in a given webmap to be more representative of what it is. For example, a parcel layer could be changed to "id": "parcels" rather than the default generated one: 17f4b9a5251-layer-13.
Another benefit would be if we had already configured an app to use a certain webmap, that configuration now references a specific layer ID. If we want to or accidentally remove a layer and re-add it, the layer ID gets changed. This would allow us to fix the app (or apps) by correcting the layer ID to the old ID.
If the new viewer could provide this functionality - it would be handy as a developer tool for those of us who build apps on the arcgis online ecosystem.
