Somewhere in the first week after we crawled out of the primordial swamps(or wherever it was that we came from) it occurred to somebody that it'd be very useful if we had a container of some sort to carry water around in--undoubtably, this person was elevated to the level of a deity, and stayed there until someone came up with the idea of a lid--

Given that, those of you who have a problem with people carrying water around in bottles, and drinking it where and when they like, are probably at least a half million years too late to change the trend.