Someone stated, during a recent class that I was teaching, that a teacher from another class wondered why anyone would want to work their camera in manual exposure mode rather than an automatic exposure mode.
Good question.
In photography, you can choose the outcome of your composition by working your camera in fully manual exposure mode or you can accept whatever composition your camera gives you in an automatic exposure mode.
I think that if you want to create the best photographs that you can and be the best photographer that you can be, manual exposure mode is the way to go.