The morality in Shakespeare's Macbeth is clear cut and absolute. The main character and protagonist is clearly evil, or to be more specific, he is clearly, obsessively ambitious and kills or orders the killings of numerous people.
Contrast this to, for instance, Hamlet. Claudius is clearly evil, but he is not the main character and his guilt is in question through about half of the play. The tragic figure, however, is not evil and suffers his fall for reasons that do not pertain to morality.
Thus, one might view Macbeth as more imprtant than other Shakespeare plays, in terms of morality.
Concerning gender roles, the reversal of them is central to Macbeth. The witches appear to be women but have beards; Macbeth, at least early in the play, exhibits emotions more often associated with women--guilt, mercy, doubt; Lady Macbeth, in contrast, wants to be more like a man: she pleads with the spirits to "unsex" her, turn her figuratively into a man, stop her from feeling emotions like mercy and kindness. These role reversals make the play important in terms of gender roles.
In fact the play 'Macbeth' becomes great for its ethical designs. some critics have considered it as a morality play. But whatever the criticisms are, the drama has withstood the onslaught of time and it is an undoubted masterpiece even to this day. William Shakespeare neither euolize nor glorify the career and life of macbeth. He direly warns the mass of humanity against the vaulting ambition and its gory effects by making Macbeth, an unfortunate victim of over ambition. As the gender politics are concerned, I'm sceptical about the greatness of this drama. Shakespeare, intentionally and deliberately, has made the character of Lady Macbeth, an enigmatic one. He sacrifices the role of lady macbeth to create a 'tragic hero', who should be able to evoke pity and fear from the audience(it corresponds with aristotle's idea of a tragic hero in his 'poetics'). In order to make Macbeth to appear less villainous to the audience, he makes Lady Macbeth more ruthless. The dramatist makes her to act as a catalyst to the evilcareer of macbeth. In the gradual process she becomes hysteric and commits suicide.