There are always some unknown reasons to get unnecessary Bspline Curves, such as extract faces/edges from 3D Solids in Civil Engineering. In fact, some / all of those Bspline Curves are linear (the total length of Curve Equal to Line from two points).

I would like to suggest tools Modify Element, Create Complex Chain, Create Complex Shape are able to convert Bspline Curves (when classified to be linear-able) to lines automatically when the option "Simplify Geometry" is clicked.

Simplifying the geometry to linestring automatically is the key success of the Microstation to handle the massive graphic of infrastructures effectively.