Josh, you must a young feller. When I was much younger, I used to crawl out of the tent at night, in any weather, at any altitude, to swing my thing in the breeze and feel that pause that refreshes. 
  
As I get longer in the tooth, there's something to be said for remaining within the warmth of my fartsack, filling the "canteen" from inside the tent, without the fuss of getting all dressed up to go out and freeze my dick off. Not to mention waking up whomever my partner may be for the adventure at hand. 
  
Mark these words, o ye who boast so proudly now of midnight wanderings. There will come a day when thou, too, shall desire strongly to remain within the confines of your cozy mountain lair to relieve the pressure that strains against your loins. Hear these words, and remember...  
  
PS: laziness has a lot to do with it, too.