People are full of prejudices even today, in the 21st century, and some of them really believe that skin whitening is a way to achieve a better social status, to gain more respect and even to get married sooner.
This concept is very old and commonly met in African and Asian countries. In the past, pale, lighter skin was perceived as a sign of distinction. Those with darker complexion were seen as belonging to a lower social class and were disregarded. For this reason, a whiter face gave a person great chances to marry in a good family, even from a higher class. It is no wonder that this idea survived for such a long time, and that it has become a true tradition.