That’s something that has to be learned and practiced with time. And yes, the overuse of CAD early on will hinder the form exploration…you can always see it in student portfolios.
Have you tried showing him/her what you are talking about with examples maybe mood boards showing similar products?
Is your assessment that he/she A) cannot achieve the design sensitivity you are looking for or B) Just doesn’t care?
Maybe limit the use of CAD in the early phases?