Jeremiah 5 - 6 - Why shouldn't I?

Here the Lord is trying to be reasonable with God's people. Why shouldn't I discipline you? Perhaps they have an explanation for the way they have behaved? Of course they haven't and God knows this - but He needs people to have their own understanding of why they are being disciplined.

Why should I forgive you?
Your children have forsaken me
and sworn by gods that are not gods.
I supplied all their needs,
yet they committed adultery
and trhonged to the houses of prostitutes.
They are well-fed, lusty stallions,
each neighing fo another man's wife,
declares the Lord.
Should I not avenge myself
on a nation as this? 5:7-9

There is a real sense of the parent fed up with a wayward child. So God, the parent, disciplines His child. The parental aspect is important here as God, the Father, will not discipline his children so much that he wipes them out. He wants His children to turn from their unfaithfulness and love Him again.

My own father was brought up in an orphanage from the age of eight and lost touch with his father (my grandfather) but he always longed to know what happened to him. Despite the terrible stories (which in the end proved to be just that - stories) my father maintained a faith that his father was loving and that he had only put my dad in the children's home out of bitter necessity. This is how God wants the Israelites to be and how he wants us to be - longing for the touch of our heavenly father in our lives.