The only way I have found to add a Loop Cut to a NURBS surface is to select an entire strip of faces and then using Subdivide.
This is sub-optimal for two reasons: if I don't select the entire strip of faces, but only part of it, Subdivide does nothing.
Also, since there is no edge or face select mode in NURBS, you have to manually select all vertices. This may be easy in some cases, but very tedious for complex surfaces that curve in 3D.
Is there a reason NURBS does not have edge / face select modes, alt-click, and most importantly the loop cut tool?