What ever gets you to the design solution... I'm sure any self respecting design studio would accept body painting and potato stamps if it somehow got you to design hit products.
With that said, I think all ideation mediums, whether sketching, CAD, sculpting... all have their pros and cons (speed, communication, type of geometry) but also have biases towards certain solutions you need to be aware of when evaluating solutions.
For example, I find it easy to fall in love with a sketch more than the product it represents. It's hard to dismiss hot sketches even though the product they represent may be far inferior to a good idea on a dirty sketch. I also think sketching tends promotes organic forms. As far as sketches are concerned, it would be hard to make an iPhone look better than a Palm Pebble. Anyhow, its hard to dismiss the efficiency of sketching as a way to quickly ideate and create discussion.
As Yo mentioned CAD has a tendency to tunnel vision your process. It's much easier to refine an idea over time than to explore avenues. Though its a great tool to explore geometry, proportions and ergonomics and can be used to make accurate underlays quite quickly. I also find CAD has a bit of an uncanny valley aspect to it. A quick and dirty CAD model where proportions aren't on point and details are missing look really bad.
Anyhow, I had this idea pop in my head today. Bias in design is not something that's discussed often.