A way to live your life
Why is hope important? Well, life is difficult. There are many obstacles. Having goals is not enough. One has to keep getting closer to those goals, amidst all the inevitable twists and turns of life.
Hope allows people to approach problems with a mindset and strategy-set suitable to success, thereby increasing the chances they will actually accomplish their goals.
Music is apparently an analog to emotion. The contours of melody, the inevitability of chord progression, the swell of dynamics, the speed at which these all unfold, all track well with the reality of how we feel.