English Standard Version (ESV)
Have you ever tried to explain baseball to someone? There are so many rules -- every time you think you have it mastered, you realize you forgot some little detail. Football is the same way -- there are countless penalties, and even after watching it for years I see things I've never seen before. Imagine trying to give guidelines to lead someone through every ethical dilemma they might face in their lives -- it would be impossible to capture it all.
Paul is trying to guide the church in Rome to live faithfully, but he knows he can't capture everything. So what he does instead is paint a big picture, one that describes the overall shape of the Christian life, and he trusts that if they are truly seeking to live as Christians, that they can figure the details out according to the big items. Love one another. Be kind to your enemies (it will frustrate them more than seeking retribution, Paul tells us). Be humble. Seek peace.
Paul paints us a big picture, and we are called to fill in the details, trusting in God to lead us day by day.