These panties have 100% less crotch than I was expecting

In my eternal quest to get organized, I ordered a wallet and a change purse from Amazon. The idea was to keep my money and credit cards and license in one place so I don't spread them across several pockets and inevitably the black hole at the bottom of my bag. In a separate package from the same company that sent me the wallet, I got this.

Panties

Not that I mind surprise underwear. Most surprises in life suck, like finding your ex-husband's emails to his long-distance girlfriend that go on and on about what a shitty mother your're going to be someday. That actually happened. Surprise crotchless panties are OK.

But I'm confused about two things:

1) The panties didn't come in the package with the wallet. They were packaged separately. So it wasn't like someone at the wallet company was daydreaming about pie and reached into the panty bin when he meant to pack the invoice. Someone knows enough about me to know that I'd be stoked about getting pink lace underwear in the mail, but not enough to know that "one size fits all" doesn't mean "one size fits all the people in my apartment building along with their pets, luggage and individually wrapped packages of cheese."

2) What use are crotchless panties, anyway? I get why someone might want easy hoo-ha access. Besides the obvious (by which I mean a quick sniff test to make sure you don't smell like sweaty hobo vagina in that black lingerie you put aside for special occasions), there are lots of reasons to dislike all that fabric. But the crotch is the whole point of wearing underwear in the first place. The rest of the material is just to keep the crotch from sliding to your ankles and getting stuck in the legs of your jeans. If you don't want the crotch, it's simpler (and probably more comfortable) to just go commando. It's like wearing a bra without the cups.

If you know why anyone would go through the trouble of wearing panties without the crotch, please share.