Why do black girls like black guys?

I think black girls aren't respected or loved enough by their male counterparts, which pretty much disgusts me in the sense that the guys are all too quick to dump them for either a really light skined black lady, or for someone who isn't black. I personally think its time for them to move on from the men who constantly put them down. I don't understand why someone would trade up someone like Jessica White (pre-nose job), Joelle Kayembe, or Toccara, for women like Megan Fox (trashy and genric without the surgery/contacts/makeup/dye), Sienna Miller, Claire Danes Anyone else agree with me?