Jesus for President, or, is the Bible Hard to Understand?

I am reading Jesus for President by Shane Clairborne and Chris Haw. I can't say I am really enjoying it, but I am reading it. In my reading I stumbled across something that makes me wonder, how difficult is it to really understand the Bible?

The authors revisit a story told by Jesus, one that you probably heard if you've spent time reading the Gospels. Jesus is talking about our response to our enemies. Broken down, it looks like this:
If your enemy slaps you on the left cheek, turn your right to him to be slapped.
If your enemy takes your outer garments, give him your underwear, too.
If your enemy forces you to walk a mile with him, walk and extra mile.

Clairborne and Haw lean towards an insight from Walter Wink on this passage. Wink looks deeper into the Jewish background and history of the time this passage was written. His deeper insight looks like this:
If your enemy slaps you on the left cheek, turn your right cheek to him, also. In doing so he will have to look you straight in the eye if he is to slap you. You no longer assume a pose of a humiliated slave; you say to him "I am on the same level as you, are you really going to slap me?"
If your enemy takes your outer garments, give him your underwear, too. When the two of you stand before the magistrate to settle your debt, you will be naked. This will shame your enemy, that he would take what you have and leave you naked.
If your enemy, probably a Roman soldier, compels you to walk a mile with him, carrying his equipment, walk an extra mile. To be seen in the company of a Jew will bring insult to the Roman soldier, stepping beyond the law that allows him to command you to carry his gear.

There's little doubt that Wink's insights add depth to the passage. And I don't question them; he's done a lot more exegetical and historical research than I have ever done. But is it too much? Couldn't the passage stand as a powerful response to our enemies, just as it is? Clairborne and Haw take it further, pointing out that the enemy is most likely the Roman soldiers and citizens, and again, probably very likely it could. But the speech isn't directed toward the Roman government. It's not the speech of an insurrectionist or political motivator.

All of the responses in Wink's interpretation seem to turn the table, raising the oppressed, offering a passive form of resistance. This passive resistance then becomes a basis for a Christian philosophy of non-violent resistance. Again, probably so. But what type of passive resistance is it when a man let's himself be tried in a fixed trial and murdered by crucifixion? Martyrdom?

But I think it is more likely that Jesus is teaching a simple lesson to a simple people. You call your enemy out by offering him the most unlikely of responses:
If your enemy strikes you he expects you to strike back. Turning the other cheek makes him think about his actions and motivations, perhaps making him realize what he has done.
If your enemy takes your cloak he expects you to either wrestle it back or try to get it back through the justice system. Offering your underwear is bound to throw him for a loop.
If your enemy compels you to carry his stuff a mile, go two. Perhaps your extra help will open a conversation or relationship with him that will break down the walls that separate the two of you.

I'm not arguing that we shouldn't look deeply at these historical and cultural views in understanding the Bible, but we should be careful when the meaning seems fairly clear that we are not reading too much. I can't imagine all these things passed through Jesus mind; instead he was reacting as the grace-filled Son of God.