my current understanding of things is as follows.
lucid dreams are there to make you realise that you are a creator of your reality. they are little tasters of physical reality. when we dream we are in the astral planes and things manifest instantly, thought = reality. the same rule applies in waking life too, things just take a bit longer to manifest. when we have a lucid dream, we become aware of the fact that we create our own reality. if this awareness is then brought back into waking life, we will break free from the limitations we impose on ourselves and gain the courage to be anything we desire. lucid dreams are also useful to practice letting go of the fear that limits us in being our full potential.