What makes their mythology unique was their belief of the future. For then, the future was already laid out and there was no way a human or God could escape it. They were hard believers in the idea of fate and there was no free will.
While us humans in Midgard may have not been privy to the machinations of fate, the Norse believed that whatever was going to happen no matter what they did. The Norse were a very battle hardened race and I am sure the idea that their future had been planned out already made it easier to go into battle.
Their decisions have already been made and they were simply following through on the great plan. The fate of the gods was well known. The gods waited for the time of Ragnarok when there would be a great battle with the frost giants and many of the old gods would die.
People generally want to know the future so they can help change what might happen. They want to prevent or cause something to occur and change how things were naturally going to play out. This would not have been possible in the Norse culture. Even if you knew the future, there was nothing you could do to change it. You could only prepare for it.