Earlier quoted context omitted.
I don't understand how one would defend their patented innovation without suing someone else? Or are you suggesting that the patent only be used as a counter-suit after being sued for infringement of a different patent? I mean, the whole point of a patent is to be able to sue people who are competing with you. How can that ever be defensive?
Unlike trademarks, you can hold a patent without having to defend it. You are not legally required to use it. So the choice to use it is yours. The logic behind defensive patents is similar to creating nuclear weapons as a deterrent and the theory of mutually assured destruction.
If IBM is not deterred by Microsoft's patents, why would they be deterred by mine?