I think mostly because I tend to associate my own fantasy with characters traipsing around forests and nature and getting back to basics. The background I use is actually the same as the one for Fantasy Factor
http://fantasy.fictionfactor.com The Papyrus font gives me the same associations. I don't know why. It just works to get me into Fantasy Mode - something I don't do well or easily - so every little bit helps.
(i prefer horror or sci-fi - no problems getting into those zones!)
Lee