It discourages scientific criticism of ideas. When you are taught a scientific fact or theory, you are always welcomed to, and often encouraged to question it. "Why is acceleration 9.81m/s^2? How do I know that it is true as of right now? If I carry out my own experiment, will I see this?" When you listen to the "word of god", this is no longer the case. You know it's right because someone, thousands of years ago, apparently said it is.
Yes, it can waste tax dollars - but we can always make more dollars. An innovative generation that can carry on mankind's survival? That's a little more important.