There is something about getting outdoors and being related to a part of the environment that resides there. Trees are cool in the summer and warm in the winter sunshine. It's like climbing under an awning during the hot months. Winter comes along and the awning is taken down to let in the warm sunlight. It's all done automatically.
Trees talk and dance in the wind.
Tree climbing is mobile. You can move to a new climbing area at a moments notice. Once you've learned the basics you can then move out to other trees or climbing locations. This opens up an unlimited arena of climbing experiences. Tree climbing is cost effective.