Your original post asked why care about spirituality. So I'll use your second definition:
a state of knowing the meaning of life, a connection with oneself and a higher being or creator. The principal teacher of values, ethics, and beliefs in it's pure uncontaminated form. Also as a transcendental demention of life beyond self where awareness and appreciation for a higher being exists
It is important to care about the meaning of life, and the connection with onself, and also values and ethics. Each person has to determine his own meaning of life, or else hand it over to someone else (like a religion) to determine it for them. I'd prefer to choose my own meaning.
If you are disconnected from yourself, you will not be consistent or progressive in your life. If you have no values or ethics, others will not be able to trust you or want to give of themselves to you.
So in those terms, it's important to care about spirituality.
As for the parts about the higher being, beliefs, and going outside yourself to connect with that higher being, you're risking going into the realm of fantasy. Some people will say these are crucial for spirituality, but I don't share that worldview.
If you're waiting for a higher being to make the world better, you're extremely likely to be disappointed. If you act ethically because a higher being rewards you for doing so or sets an example for you to copy, you aren't doing it purely out of the goodness of your own heart or your love for humanity. Remove the external influence, and you're doing it because you're being good for the sake of goodness, which to me is the purest motive.