Why it is important is because it tells a story about what's going on in your emotional state that you're otherwise unaware of or repressing in conscious experience. It can also provide solutions. It can be a powerful tool for maintaining mental health and wellbeing.
This isn't to say you should be reading "dream interpretation" guides or speaking to interpreters. The point is we already speak the languages of our own dreams because it's our own mind. What seems like nonsense on the surface quickly reveals itself to have a surprisingly clear meaning on introspection from a slightly different angle. Follow your intuition, listen to your psyche, you wont regret it.
The problem with using guides and interpreters is that you don't know whether they explain your unconscious associations, or just substitute their own.
If you interpret your own dreams, you can be sure that all associations were generated by your own brain. Maybe during the dream, maybe during the interpretation. Who cares; either way, it's about your brain.
My simple interpretation method is to write an outline of the dream, and to some words add an arrow and write what it reminds me of. Usually at least three things in the dream remind me of the same topic -- that is the core message of the dream.