I could never see the point of the G-string (I'm not going to call it a thong, because to us Aussies, that's a shoe).
I mean, what are panties for? To form a barrier between your clothing and - er - bodily effusions. That tiny bit of floss at the back isn't big enough to protect anything. True, the shape widens out at the crotch - but put the thing on, and that part immediately squishes up and slides straight into the crack. How is that hygienic? You might as well go commando, if that's all you're going to wear.
I do wear a g-string sometimes, but only on occasions when I'm wearing little or nothing else...