Even a mere human mother nursing her sick child would do anything she could to make her child well. That's more than god would do.
But he did do it, through Jesus. Your question about 'why didn't God just forgive - why did Jesus suffer' is an excellent one, and one I've thought a lot about myself - I struggled with it for a good while. But then I began to see that if Jesus had not come and been on the earth as one of us, and gone through that death, God would not be 'God with us' not God incarnate - and have no comprehension of our own suffering, our own lives with their ups and down, triumphs and tragedies. I can look at Jesus and know that he knows how I feel when I hurt so much I can barely go on, and when I am struggling for breath, and when I am heartbroken. He knows. God knows.
If God just said 's'ok, I'll forgive you, it's fine' it just downplays the huge seriousness of how messed up this world is, the terrible things humanity have inflicted on one another. It cheapens it and wouldn't mean a thing.
But instead, he got down and dirty in the midst of it. He spent time with the dregs of society and loved them. He built up women and lepers. And he suffered a horrendous death.
And that's even before the resurrection. He beat death. Death doesn't have to be the end, the final curtain as it were, because it's beaten. I'm not a great fan of penal substitutionary theory, ie Jesus took the place of animal sacrifice, but see it as more of a victory over death. An incarnation, a complete understanding of what it is to be human, suffering and all, and then a pointer to the hope.
So God saying 'I forgive, don't worry' just doesn't cut it. It's so, so much huger and so, so much more powerful and incredible.