The n word was considered completely verbotten for many years until the mid-80s when it started to reappear as a fraternal term between rappers and hip hop artists, and from whence it became part of youth lanaguage. There's an interesting article about it here:
http://abcnews.go.com/sections/Downtown/DailyNews/downtown_n word_020410.html
Also, the NAACP (North American Association for the Advancement of Coloured People), one of the leading bodies associated with the civil rights movement condemns the word still.
MOBO was started because the mainstream awards ceremonies did not recognise achievement by black musicians, and in music which had black origins, such as hip hop. However, the awards are not restricted to black people. It would be pointless setting up MOWO since this is essentially what the BPI is already.