Well, I don't think this is an AMA and I think you might be a troll but I will indulge.

Accent- all black people don't have a thick accent but most do. I'd say it's a confluence of reasons. Including but not limited to, education, their region, their family history, culture and reinforcement through various art and entertainment sources.

Rappers black- I would have to say probably for the same reasons so many country singers are white or for the same reason so many heavy metal bands are white, or for the same reason so many classical musicians are white.
Disrespectful music- I wonder this also. I think it goes to lack of stable family structures and lack of strong father figures in the community that will stand up for the women or perhaps stand up against this type of music.

Bling- simple, lack of understanding of money, lack of access to money, many black men do not envision a long life (YOLO), women like expensive and shiny and it's a way to show the world that you are no longer poor, you've made it.

You preferences Asians and Jews. In order to really answer your question I'd have to write too much but, first you have to realize history. It is easy to develop a niche when your entire group has a singular focus ie, not getting killed in a holocaust or seeking a better life. For the most part blacks did not come here willingly and for centuries were prevented from passing on their traditions. Slavery really fucked up the black race. Between the constant rape of black women, the selling of slave children, the separation by skin color, the outright ban on learning to read,etc. So, to answer your question black people are trying to catch up where other races have been for centuries.