*Paul*
Jesus loves you
This is the very same question that I posed to some JWs. They told me that God would judge them on their lives, because no one had explained the Word of God to them.
So, not knowing the Word = salvation as long as you lead a good life.
Being told about the Word but not accepting it = damnation, despite your life so far.
Therefore, missionaries all over the world that go round explaining God's word to those unaware of it have undoubtedly caused the damnation of millions of souls who, upon hearing of God's Word, could not accept it, for whatever reason, but who had thus far led blameless lives.
Telling them they are directly responsible for damnation gets rid of them from the door pretty quickly, I find.
I agree with you completely, it would be an act of malice by jesus Christ to instruct us to go into all the world and teach the nations and make disciples, and if they don't believe they shall be damned if by not hearing the word they get to go to heaven anyhow.
It makes more sense as a rescue mission.