Hi Jamie, that kind of combination polyline + a special option just for arc has always seemed to be just a bit odd to me, particularly because in how it behaves when you try to make a closed curve.
The methods that I have seen don't allow you to get the same kind of result at the close point as you would for a filleted polyline  I guess that's the part that seems kind of a little strange.
Also chaining a whole series of tangent arcs together is something that you might want to do if you are trying to manually draw some GCode that is constrained to only be able to do lines or arcs but for more regular NURBS modeling purposes having a smooth control point curve tends to be a better way to do a longer curved shape instead of a chained bunch of arcs.
Do you have an example of some models where you wished you had this function to help you out? If I could see some examples that might help me to think about it some more and to see if some issues like the closing point would be significant for your cases or not.
 Michael
