Use could be for temporally fixing broken legs. By using whiskey you get dazed, your screen shaking or bobbling will make you hard to aim, bright light makes you have similar effect as after using night vision, hard to walk or slower walking time.
Yes that would be use full I yesterday got a ATV and flipped it on the first bump after 2 hour part searching :[ I cant think of any reason why this is not already in the game.