There is nothing wrong with trying to be a shade or two lighter. Its personal choice.
Do you ever see debate about why White people always try to tan their skin?Color their hair black to blonde, blonde to black?Wear contact lenses? Does it mean that white people suffer from inferiority complex and they are tryna look like brown people?
I reckon all this has got nothing to do with inferiority complex, or after effect of colonization or other more complex explanations that people came up with in this thread.
Its more to do with the human desire to stand out, to be unique, to get noticed! If them majority of the population is mocha brown in color, and your skin is milky latte, you ll stand out and get noticed, and who doesn't like that!
But discrimination based on skin color, that is definitely wrong.