Mystical prayer is essentially an experience of unity with God and God's creation. Kything is a gateway to mystical experience and can foster deeper prayer states. When you kythe you transcend separateness without losing your identity. When you kythe you enter into a state of unconditional love and spiritual union.
As a hasidic master once wrote about experiencing this spiritual energy while kything with nature:
When you walk across the fields with your mind pure and holy, then from all the stones, and all the growing things, and all animals, the sparks of their soul come out and cling to you, and then they are purified and become a holy fire in you.