In that case the tool would need to lay out everything holistically but while it might do great arrow wise it could be useless for the user if they wanted the diagram a certain way for a reason.
Yes, that is what I've noticed too. On medium/big projects macro-level(holistic) arrow functionality is far more important than having beautifully curved arrows from node A to node B. Solving that problem strangely resembles routing on a circuit board with buses, labels, colors, layers etc.
