Exactly! A knowledge of the liberal arts is also essential to understanding how people relate to STEM. I would say that it is essential, unless you want to become someone stuck in a back office receiving requirements by email and passing back code through a small window. Fortunately the number of people I've actually met who actually conform to this stereotype is very low! But it doesn't hurt to learn a little bit more, and a lot of pain has been caused by developing technology with no regard to how society functions.
A more general view: the development of technology affects the development of culture and vice versa. I think that if you only understand one side of this picture, the future is guaranteed to catch you by surprise.