First I’ll start by saying black is beautiful. All people of all colour and shape are lovely beautiful creations and should be appreciated.
Skin lighting can be used to treat medical conditions like hyperpimentation (patches of darker skin due to increased melanin). The cosmetic one just to look lighter is due to pressure from society that fair is lovely (like the advertisement for the cream fair and lovely). Some of the skin lightening creams have bad chemicals like mercury or hydroquinone that are very harmful. Some skin lightening creams are made form high quality or natural products and are fine to use. These natural and safe ones are very expensive. Other methods of skin lightening are available, e.g. laser treatment or plastic surgery, all can be done safely if the right procedures are followed and by the right doctor.