There is something to be said about the size of a brush (or pen nib) in relation to the size of the paper on which it is used. There is a limited amount of space within which to maneuver with a large pen tip or wide brush. This is the reason that wide brushes work so well with washes. Limited maneuverability is preferred when creating an even wash.
My blue ink abstract is the result of taking my medium sized pen tip for a walk, enclosing certain areas and deciding which colors to apply to each area.
I like the boldness of the lines and colors. But I also enjoy the disintegration of some of the pen lines and the subtle variations of some of the color fields.