A good graph layout tool does not only provide many fast layout algorithms, it also includes powerful interactive operations to browse the resulting picture. Usually, the layout is shown in a window on the screen. If the graph is very large and does not fit in the window, either only a part is visible or the picture must be shrunk. If the visible part is very small, the user often looses the orientation during the navigation through the graph. If the graph is scaled too much, details, e.g. labels of nodes, are not readable anymore.
