Who cares what an over 2000 year old book says about morality?!
Most modern Americans identify as religious of some form or at least spiritual. Everyone knows that Christianity has acted as the basis for a lot of the early Western Culture we know today.
Given that a large number of Americans believe that there is a God and most of them believe it is the God of Abraham and most of them feel their entire moral code comes from that God then it is critical to understand it.
And finally: the DIFFERENTIATION between our modern morality and one of an ancient peoples could not be more stark. The acceptance of those who were considered at the least "unclean" and at the worst an "abomination" is a good thing. We are better people than that. And, ironically, Jesus himself seemed to open the door for that kind of approach. HIs love and acceptance stuff truly seemed a revolution.
Which is what all religions ultimately need over time. A revolution. But if one expends too much time laboring over how the plain language of the text doesn't say what it says and instead says something completely different then one runs the risk of removing all value and meaning completely from the holy word.