Why does Islam allow hitting the wife as mentioned in Surah Nisa, 4:34?

Everywhere in the world from the beginning of time men have been hitting women.  Even in the countries of the West which ban it, the majority of women still continue to be hit. In fact, the cause of death in majority of the women was from being beaten to death by their husbands in their own homes.

Islam restricted hitting to only one occasion, to save a marriage, and even this hit was restricted to a pat on the shoulder or behind which should not bruise the skin or leave a mark!!! That was 1,400 years ago? Where else in the world could you find that?