If I understood you well you mean curves of functions. Well yes they are very important if you want to create an engine, then you create the curve of the noise, or the curve of the oscillation. Also when you want to create a bridge you need to make the curves in order to apply the physics. If you want to send a rocket in space you sketch the curve which is the orbit. Also for ecology, you can see from the curve of the temperature that global warming exists and you can predict things too. During the war, the planes have computers that calculate curves in order the bomb to find the target and not to hit a home. Curves are the visual representations of mathematical functions and they are very important. Also for economy, the curves can tell a lot about the market, the goods and the economy of the society. I hope you got some ideas.