Hi Danny, yeah the geometry library function that is being used for making the tapered extrude requires a closed loop of curves as part of how it works - it constructs some planar faces for part of its calculation and that's only valid with a closed loop. So yeah that's only something that can make stuff from closed profiles currently.

Also as a side effect of the particular way it does its construction it does not have any way in it right now to turn off end caps, that's why the "Cap ends" checkbox gets hidden when you engage the tapered extrusion.

- Michael