A Straight Word

I often say, "Maybe," when someone asks me any question! It's a normal thing in Japan. But Americans require you to say to them, "Yes or No." One day, an American asked me about a problem, but I didn't know the best answer. So I said to her, "Maybe." After that, she said to me that that she wants to hear, "Yes or no." I was very confused by her words! Americans require "Yes or no." First, why do Americans require the answer "Yes or no?" They want to hear the clear answer. It's very straight and American style! Second, why do Japanese people escape telling someone straightly? Because, I think, they don't want to hurt someone by speaking straightly. Third, if I really don't know about a problem, how can I say that? It's easy! I just say, "I can't decide," or "I don't really know." At first, when I heard her words, I was confused about that, but I have to understand their style now. I think that I wanna know more about American style now.