I believe consciousness exists because we are meant to use it.
It comes from within and is part of our 'innate self'.
When we live without consciousness we go about our activities without any connection to or awareness of what we are doing. Many people drive for periods of time so busy thinking or worrying about other things that they arrive at their destination with little memory of the actual trip. Quite a scary thought really.
Consciousness is stimulated by living in the moment; being fully engaged in what you are doing at the time without thinking (as most of us habitually do) of the past or the future.
Fantastic question andrew, bet you get some interesting answers.