I think the reason we are not always lucid is more of a social conditioning thing than a capacity that we have recently developed. At present, I think the human race in general is narrowly focused on the material physical sensory world rather than the internal world of sleep and dream. I think the world we live in (the system) promotes this sort of single-minded materialism by marginalizing dreams as unreal or unimportant. We are not encouraged to explore our consciousness beyond the waking life.