I'd like to see an add x y coordinate tool for feature layers in AGO web maps. X Y cords in lat long decimal degrees would be excellent.
Users using new Esri tools such as trek2there that requires lat and long fields from the attribute table as input https://blogs.esri.com/esri/arcgis/2016/12/22/introducing-trek2there/ would benefit, and AGO users wouldn't have to add x y cords in desktop only to republish a layer with x y cords.