Some people enjoy being in nature. Why? No, don't tell me how you love the sound of birds or whatever; I'm looking for different answer.
I believe that for every urge there is a reason, something that makes people with that urge more likely to reproduce than with not. You know what I'm talking about. So what's so cool about nature? If indoors living is such a new invention (coupla thousand years? What? Did they really spend that much time in caves, the cavemen? Were there even such thing as cavemen?), shouldn't the "indoors/outdoors" preference be neutral in human heritage, instead of clear "outdoors" preference some have?
Yes, I see that fresh air is good for you, some sun is good for you, but how should human's heritage know that if they never had lived indoors enough to make the difference in evolution?