In my last Glock armorer recert last year we were told that Glock's introduction of the the G42 was the result of the fact that the fastest selling commercial (non-LE) caliber in recent years was .380 ACP.
Reportedly, the fastest growing segment of that market appeared to be women shooters. Thus, their G42 being chambered in .380, and it being large enough to offer a pleasant shooting experience, especially for the growing number of female shooters. Maybe so.
It helps that there's been some added focus by the major ammo companies in the way of offering some newer JHP loads, too.
The Ruger LCP and S&W Bodyguard .380 have certainly been doing brisk sales.
I'm not interested in a SA/cocked & locked .380 for pocket holster use, myself, but the little SIG's seem to be doing well, too.
I picked up a 2012 vintage LCP (carbon steel slide) because I wanted something shorter, thinner and lighter than my J-frame snubs. (Some of my jeans pockets are too tight/short to conceal my J's, and I'm past the point of wanting to always "dress around" a weapon.)
The little LCP was quite a surprise. Handy, light, short, amazingly accurate (even when using the rudimentary sights) and reliable with an assortment of JHP loads I tried.
I liked it so much I decided to pick up a 2014 vintage LCP (stainless slide, and improved sights & trigger). The G42 and M&P BG380 were just too much bigger than I felt I wanted.
The new stainless LCP was even better than the first one.
If I'm going to carry something larger than a LCP, it'll be one of my J-frames, or the smallest of my smallest 9's, .40's or .45's.
On consignment sale.
