The major reason I like having a drinking tube attached to a 2 liter Platypus in my pack that i can grab and drink from at once, as opposed to a water bottle in my side pocket that I must stop and remove so I can drink from it, is that I find I am more willing to drink water the moment I feel thirsty regardless of whatever else is going on with the trail or my surroundings. So, I stay better hydrated.