Hope is an ideal that one can use as fuel to move towards. Despair on the other hand is a reaction to what has come before.

Both of those are vital components of the human condition, and without them the vast majority of human emotion and effort becomes meaningless. Hope and despair are intrinsic to humanity and it’s progress.

Why bother changing anything if you have no hope for the better? And why bother making those changes if you feel no despair at the present situation?