Inhospitable Earth
"The great biological diversity that you enjoy and that represents such splendor in your world poses a great dilemma for advanced races, many of whom have evolved in more sterile environments. Living here is difficult because of the biological diversity itself.
Another disadvantage to your world is that human beings live above ground, which is not preferred by most advanced races. Underground settlements have proven to be far more effective and accommodating, especially when you are actively engaged with other Greater Community powers. This gives you greater security and a greater opportunity to protect your physical resources and your population at large. However, living underground isolates you from biological elements in the outer environment, thus making you more susceptible to illness and attack by other kinds of organisms."
- --Greater Community Spirituality, Chapter 6: What is the Greater Community?