It is because how we understand the kind of book Revelation is will determine how we read it and what we expect from it. In so doing, we can avoid the misunderstanding of the meaning of the author John intended to say.
I have learned that the book of Revelation resembles three type of literature that were familiar to John the author and the first readers of the time. It has clarified my understanding of prophecy which is not only “fore-telling” of future events but primarily also “forth-telling” the immediate audiences of their problems/issues and urge them to change.