The people of the day were ignoring the teachings and sermons of the prophet so the only way to get their attention was to use more poetic speech. While we can still see some of these literary devices in the prophets that we read today in the English translations, there are even more play on words, meter, and devices that we cannot see or understand in the original texts!
This is a really cool area of study if you ever have the time or interest in it. Check it out!
