It could be really helpful to have a modifier that allows you to extract edges as Splines without breaking the proceduralism of the stack letting the user working in a non-destructive way. Like in the other case, when you create an EditPoly from a Spline, you can edit your spline and the edit poly will update, it could be really helpful to have an spline that updates depending on the EditPoly modifications.
I've seen this kind of workflow in other packages like Houdini, I guess something like the Carve tool.
