The story tells us that god didn’t send the Israelites to exile to punish them. He doesn’t need to punish anyone. Rather, he sent them to exile in order to bring an end. He did it in order to force some humility and repentance in his people in fort of the true god. There lives of sin and rebellion had washed any remorse from them.
The punishment was god’s way of reminding them that he existed. They were reminded of their humble identity and the majesty of god. God had sent century’s worth of messages and warnings to his people to no avail. Finally, it was time for some physical reminder.