1. They are often the first stories youngsters come across and are a gateway into the wonderful world of reading. Once that spark is lit, there should be no turning back. It is no coincidence that those who read more develop a larger and more wide ranging vocabulary.
2. There is a clear sense of right and wrong in fairytales. (That appeals to children and those who decided growing up was overrated).
3. Some stories can act as warnings.
4. The stories can reflect injustice and cruelty but also usually have those things stopped by the end. (In life so often these things are not stopped. It is good to have stories where matters are rectified, justice is done etc. This is something shared with good crime stories too).
5. They're great stories (reason enough!).