To answer your question, is prophecy important I would say yes. The fact that I can think of six off the top of my head that did not come true shows me that the bible is not a holy book written by god. The six I speak of are the destruction of Trye by the Babylonians they were unsuccessful and it was later rebuilt after Alexander a Greek destroyed it. 2. Damascus to be destroyed and be a pile or just a heap again didn't happen after the verse was written in Isaiah. 3 the Babylonians were to conquer Egypt again didn't happen. 4 Egyptian's were to find themselves speaking Hebrew or some other Semitic language again didn't happen. 5 Jesus told his followers that some of them would not die before he returned, again didn't happen.
6 the Davidic line would always rule, again if there was even a Davidic line it stopped after the Babylonians destroyed Jerusalem in 587 B.C.E.. Yes some will argue that a kingly line did still exist and one even was present after they returned from Babylon (if you believe the Bible) but the Persians did not allow a king on the throne at Jerusalem and no Davidic king was again on the throne until Jesus supposedly showed up over 400 years later.
I'm sure there is more prophecies that I don't mention like the one in the last chapter of the bible where 5 times its says Jesus would be back very soon, but hey whose counting.