Here's a datapoint for the discussion, from the just-released ATF 2016 Annual Report on firearm production in the US, that shows how popular the .380 Auto caliber is becoming:
Pistols produced in the US (by type)
.22: 447,315
.25: 13,141
.32: 10,175
.380: 1,130,459
9mm: 2,281,450
Over 9mm up to .50: 837,535
Total: 4,720,075
S&W produces many models in every major caliber, but before the 380 Shield EZ, really had only one .380 Auto model - the Bodyguard. This is an important part of the market, and S&W now has another pistol to offer the public.
Source:
U.S. manufactured the most guns ever in 2016