Philosophy of a person's expertese

I have an interesting dilema. It seems that I have two contradictory beliefs about how someone should develope themselves as a person. My first belief is stated in Plato's Republic. In the first chapter Socrates states that people should only develope themselves to do one trait and people should focus on different areas. Thus one person would be a tailor another would be a carpenter. They can trade their services and so the tailor would get something like a chair and the carpenter would get clothing. This would eventually lead to money and a wel running sociaty. I also believe that one should be well-rounded. That is that one is a physisist but also delves a little in psychology or philosophy. Can someone help me. Do you believe the first ideology is too old-fashioned.

Get a solid general education, and specialise in one field. Most if not all of history's greatest geniuses were interested in things other than their specialised field.