A very mature answer, my own are quite similar, Keyblades should be used for what we need and what we want, but still used in a responsible way.
Exactly like Mickey and MX, Darkness and Light make up the worlds, "You can't have one without the other" as quote by the Fairy Godmother.
You forgot what you think of each, I believe Darkness and Light are both two different sources of power (much like Xemnas' Hypothesis) Light being a much more safe, quanitative power, while Darkness is a much more darngerous and qualitative power.
Edit: I believe Light and Darkness can both be used for good or bad.