Parametric primaries only matter if you are going to need to change them. As a designer it's HUGELY important to me to be able to easily adjust my surfaces based on changes to the internal engineering of a product. As a reverse-engineer or a traditional class-a surfacing person, it may matter less.

Many automotive-quality surfaces are built with almost no parameters or history. But in consumer product design, that simply doesn't work. It's critical that we be able to adjust the surfaces to do modifications to the product. Perfect example: imagine you're designing a power drill, and the handle has an 8degree angle to the motor housing. You print the model, and decide that the handle should actually be 10deg. Should you then have to blast the entire trigger lip and blend surfaces, only to adjust your primaries and rebuild them at 10 degrees? That's crazy talk!

If you don't think you need parametrics, you might as well just use Rhino!