Most people consider Shakespeare to be a contemporary dramatist. His work has poetry, meter, form, imagery and is known for its memorable speeches. A lot of the stuff above seems very pedestrian to me.
Check out Lorraine Hansberry’s A Raisin in the Sun and the plays of Athol Fugard, and possibly _RENT- which deliberately has an ethnicly diverse cast.
“Athol Fugard (born 11 June 1932) is a South African playwright, novelist, actor, and director who writes in English, best known for his political plays opposing the South African system of apartheid and for the 2005 Academy-Award winning film of his novel Tsotsi, directed by Gavin Hood…
The recipient of many awards, honors, and honorary degrees, including the 2005 Order of Ikhamanga in Silver “for his excellent contribution and achievements in the theatre” from the government of South Africa, he is also an Honorary Fellow of the Royal Society of Literature.”: http://en.wikipedia.org/wiki/Athol_Fugard