I think the ability to carry a bottle of water for immediate access is a useful gadget. I always find in the Summer and when touring abroad in warm temperatures that at every stop I am gagging and need to rehydrate - so having a bottle of water to hand seems a sensible and useful gizmo to me.
Not much use if you've got a full face lid on tho' unless you stop and take it off.I use a camelbak ,a small rucksack thingy with a bladder in which holds 2 litres of liquid.I just stick the tube up under the chin piece of my lid and have a slurp as I ride along.Seems to keep the liquid cold even on hot days,brilliant piece of kit.