Unfortunately, the new saying in STEM is that a B.S. is BS. Grad school, especially from a well known school, is sort of like the ultimate stamp of approval that tells employers "this person has a certain skill set worth paying for." Of course, there are many people that do not need grad school to make an impact in industry almost immediately. However, it is one of those 'nice to haves' if you want to jump into any sort of highly technical position.