It isn't that there is intrinsic value in the various other subjects themselves, the value comes from having a shared core of knowledge / experience that can be used when interacting with others. Just two examples from recent conversations -- once I used an example that had a comparison to a canary in a coal mine. Several people in the group never heard of that phrase, so I had to explain what it meant. Another time I used the expression "Tilting at Windmills", and again that was lost on some people.
So yes, it is important to be well rounded, just to have common base for general conversations.