So I have been reading the Silmarillion, and Melkor is indeed a very spiteful role who seeks to destroy and corrupt everything that is good. But I also realized his personality and power is quite limited. Melkor is constantly jealous and afriad of things more powerful than him (or we may say that anything that stands against him). He's fretful of Tulkas and Orome and even a big hungry spider. When he fails on some point, he just simply run back to his basement and hide for some time. He somehow look like some vicious, mean jealous bully who is both a destroyer and coward too lol.
Look, I’m not saying that Morgoth is incompetent or stupid. He is very intelligent and corrupted, but I suppose the price of evil is that he’ll never find true courage and honour even when he has to fight back. His hands will never be healed from holding the Silmarils, which I assume it as a sign of how light and goodness will always be insufferable to him, and he will remember that for all eternity.