Why has God made men protectors and maintainers of women in families?

Verse 34 of Chapter 4:

Men are the protectors and maintainers of women, because Allah has made one of them to excel the other, and because they spend (to support them) from their means. Therefore the righteous women are Qanitat (obedient), and guard in the husband's absence what Allah orders them to guard. As to those women on whose part you see ill conduct, admonish them, and abandon them in their beds, and beat them, but if they return to obedience, do not seek a means against them. Surely, Allah is Ever Most High, Most Great.