Someone's skin color really is a pretty inherently large part of their physical presence and if they're going to permanently change it because , how is it not self-loathing?
Is a sex change always self-loathing? Yeah, I went there, and I feel it's a valid question for you. Most people would agree that your sex is a big part of who you are--bigger even than skin color--but as making changes to that is a rather protected right here on GAF, most people wouldn't (shouldn't) agree with your blanket statement on changing inherent physical characteristics being a form of self-loathing across the board.
I know at least one person posting in this thread (not you) who vehemently crusades for being comfortable with your body when it comes to gender identity and whatever permanent physical transformations that entails (and I agree with them there), yet they seem to be generalizing these skin color transformations as so terrible, so tragic. I disagree.
The reasons why most of these bleachings happen are terrible and tragic as adequately described already--that black people are made to feel inferior by society from an early age while having to see all these beautiful white celebrities glorified in the media, to see that life is generally much easier as a white person etc.--but I'm not going to generalize it all as self-loathing or a travesty; some people just want to be in the body they feel happiest in, and it's not always because the world made them feel that way is better. Even if that is why they did it, until we can change that society sends some terribly unhealthy messages to females and minorities, I'd rather these people be happy with themselves than miserable. If they can come about that no other way I'm just happy for them if they finally reach that point.