wrl is an approximation of the surface via triangles.
This is most seen for curved surfaces. A drilled (circular) hole will be approximated as a n-polygon hole.
Step works differently here. It is a precise description of what has been designed. (Simplified: A circle is represented by its center position, the description of the plane it is on and its radius.)
There seem to be ways to create a step file from a wiremesh http://blog.bantamtools.com/convert-stl-to-step
But these do not get back the lost information. The step file generated will be useless for most cases where you would want a step file. (Example: A CAD program will not be able do identify a hole as a circular hole with a radius. Meaning it can not generate manufacturing drawings. You will also be unable to use these holes for the basis of constraints in assembly designs.)
There is a reason why we threw away all old wrl files from the new kicad 3d library. We now suggest using freecad to design 3d data and step-up to export it in both wrl and step. (wrl for nice renderings as it allows better material additions, step for communicating with mechanical CAD programs. Mainly for the exact usecase you describe above)