I worked line service when I was 18 during the summer. It was an awesome job that paid very well for me at the time. It was fun work. I got to meet a lot of people, and I learned a lot of interesting stuff that I am and will continue to apply in my flying career.
I agree that all pilots should have to do a "tour of duty" as a lineman (1-3 months). It is a great learning experience. Especially for corporate pilots. I could always tell which pilots had worked the line becuase of how they'd treat us. Even if a problem came up, as long as we explained it, they seemed to understand. Others were just jerks.
Net Jets pilots were always the best to us.
Citation shares pilots always had big egos.
I have never worked line service in the cold/rainy winter, so I feel for those guys.