And beyond just getting ripples and bumps, applying sub-d smoothing just generally produces a sort of melting effect, which means that various aspects of your model's shape will be altered in a NURBS to Sub-d conversion attempt.

So that whole process of a NURBS to Sub-d conversion would be pretty weird - things like crisp accurate mechanical shapes (which is normally what you want to be using a NURBS modeler to produce) will become kind of melted saggy things potentially with ripples and bumps in areas that used to be perfectly smooth in the original NURBS model.

Certainly there could be uses for that kind of melting mutation, but it's kind of a weird and poorly fitting workflow since the advantages of NURBS modeling are that you can produce crisp and accurate stuff with it.

If you want melted non-mechanical stuff, you should most likely be creating that as a sub-d model from the start rather than trying to use a tool like NURBS modeling that has a completely different focus.

- Michael