Add custom shape/image in appearance panel
Now one only can add rectangle/circle shape in apperance panel. It would be very useful to be able to add custom shape/image/symbol there also.
Sorry, do you mean Effect > Convert to Shape effects, Rectangle and Ellipse?
More parametric shapes here will help to create more interesting graphic styles for sure.
If it allows to add a custom Symbol... should it be used it as it is? or United first? what will happen if a user deletes a symbol?