Going full offense, no matter how active you are, means you are taking a much larger risk for practically the same benefit as keeping a minimal defensive force around. All it takes is one small mistake and you can be royally screwed. And before you tell me that you are a super player who doesn't make mistakes, everyone makes mistakes, or gets caught in a situation you can't win, once in awhile, no matter how good you are.
Let me give you an analogy. Look at most of the aces from WWI and WWII. Aggressive, dominating, these are the traits they displayed, and it kept them alive through countless dogfights. Yet, you know how most of them died? In dogfights. Even the Red Baron, a man responsible for the emergence of countless tactics for dogfighting, and thought invincible by people on both sides of the war, died in a dogfight. You know why? He made one little mistake, and paid for it with his life, like countless other pilots.
So, think of the minimal defense as a parachute. It might not even keep you alive completely, but you sure as hell have a better chance of reaching ther ground safely should you make a mistake that is exploited by someone else.
