The C-string is designed for women who find the thong too dowdy. Referring to it as underpants is like calling Roast Bacterium an entrée. It is an attempt to reduce the underwear to its most essential part. If you wanted a more minimalist approach, you could just knit your pubic hair in place.
I did make an effort at modernity once. My friend Gina’s daughter had bought her a thong and she instantly passed it on to me. “It’s clean,” she said. “I only had it on for five seconds. You try it.” In spite of the warning implied, I put it on, found the hand-mirror, checked out the rear view, somebody screamed, and then the thong completely disappeared, leaving behind only a sensation I had not experienced since we got rid of the bad toilet paper.
On its face, I distrust underwear with a lot of engineering in them. I might make an exception for an edible chastity belt that required suitors to earn their way in. Otherwise, keep it simple.
Men’s underwear, if anything, is even odder. The briefs do seem to offer something in the way of support or confinement or hiding-away. I don’t have anything flapping around in that area, so I don't know if perhaps a certain swaddling is a comfort. But boxers don’t seem to have any function at all. Boxers are the towel on the parakeet cage. Just something to throw over the occupants to settle them down. They’re there to let the wearer know there are even larger pants on the way. They’re like a training tool for the junk-whisperer: here’s a tiny, lightweight pair of pants, they say. Are we all right? Good? Okay now. Let’s try something a little bigger. Their main function is as a first-responder in a crisis flatulence situation.
Back in the day, it was popular to have underwear emblazoned with the days of the week. I can tell from my vitamin-dispenser that that wouldn’t work out well now. At some point I’d be wearing Tuesday and Wednesday at the same time to catch up. There really isn’t much of a point to underwear at my stage in life. Mostly it’s there to fend off the trouser seam when I bend over. With a long enough skirt, I know a way to get panty lines to plumb disappear.