From my limited experience, many players and DMs seem to get things backwards in exactly the way you're describing. They take the rulebook as the starting point or the "controls" for the game and since combat is the most detailed they tend to focus on that to the exclusion of other parts of the game. I've always viewed the rules as a way of settling disputes or uncertainty instead, so you start from the role playing and only resort to rules when you need fair adjudication or clarification on complicated situations. i.e. don't give me quotes from the rulebook, tell me what your character does and we'll work it out as part of the story.