I have an $800 pack - I decided it was worth an extra pound of tent weight to have the room for my pack inside with me {with all of my gear in it]. Turns out it probably didn't take an extra pound.

Anyway depending on where you are and what you are doing, your life could depend on that pack and gear, and leaving it outside, to my way of thought, is just asking for an epic trip. I know people who hang everything in a tree and turn their pack out for the animals to have their way with. My stuff including first aid kit, tooth paste, suns screen and lip balm stay next to me.
Jim