Downer. Way to kill a thread, PIB.
Anyway, light beer can come in handy when the night revolves around drinking. If you're playing drinking games or just with the kind of crowd where you know you'll be downing many a brew, it's good to have something that goes down easy and isn't as alcoholic.
I'm not sure if the calories game even pans out, since light beer is less alcoholic you have to drink more of it, and I think there's more to beer than calories that makes you fat