I'd agree with you to a certain extent, but the concept of man being saved completely apart from our "good deeds" is at the heart of the Gospel. That's the rub.
If it were a simpler and less critical issue, let's say whether or not there is a Purgatory, it wouldn't be so important. This, however, is as basic to our religion as anything. True Christianity is different from all other of the world's religions for NOT positing that we will be rewarded in the afterlife because we flattered the gods or the cosmos.
I'm just saying that this is why the definition of these terms and how they interact, if they do, is something that we can't just pass off as less important than doing good because God, obviously, wants us to.