In Shakespeare’s day, women were generally expected to do what their husbands told them. This is why Lady Macbeth’s behavior is so unusual. In fact, she makes several references to her mannish nature that can lead us to suspect that her behavior is unusual and Shakespeare did not approve of it.
It seems, first of all, that a woman is not expected to be cruel. Lady Macbeth actually asks to be “unsexed” to secure cruelty.
Come, you spirits
That tend on mortal thoughts, unsex me here
And fill me, from the crown to the toe, top-full
Of direst cruelty! (Act 1, Scene 5)
She wants the courage or brutality to kill Duncan or encourage her husband to do so, or at least come up with a plan.
Just because Lady Macbeth is not acting like a traditional woman may not make her more or less evil to us, but she certainly would have been a less desirable character to men in Shakespeare’s time. Even Macbeth comments on it.
Bring forth men-children only,
For thy undaunted mettle should compose
Nothing but males. (Act 1, Scene 7)
Lady Macbeth is more evil not just because she is not acting like a woman, but because she continually pushes her husband to act in evil ways—such as murdering Duncan and the guards.