I actually think it is not totally historical accurate to say that interracial relationships have been taboo for so long. I think that they became more taboo after slavery, when white people in the U.S. and especially the South wanted to make sure that black people would continue to be oppressed. In the time period when Shakespeare wrote Othello, I am not sure that it was as remarkable as it looks to us, looking backwards. In the 1600s and 1700s racism was not fully developed and there may have been more flexibility before U.S. slavery was fully established. After all, Othello is called The Moor, not the negro. So I think that historical context matters in understanding race.
But at the same time, there is no question that marriage laws are a way that society decides who does and doesn't have rights. I think there are so many taboos on marriage (gay marriage, interracial, interfaith) because people see marriage as a way to structure society. Whether you are married, how many times you are married, who you are allowed to marry: these all are seen to reflect on people's place in society.
As for comparing the Lovings and Othello/Desdemona: both couples are in love, though there are class differences. The Lovings were average people (he was a bricklayer), and neither was the child of a political leader or a military hero. Although, I never realized that Mildred was African American and Native American, because people talk about them as black and white. Finally, the story of the Lovings shows how hard people had to struggle to get basic rights that others took for granted.
