Lots of different influences probably coming together at this time.
I remember when they had me turn in my service revolver and take in its place a hi-cap aluminum-framed 9mm pistol, and the primary explanation was that we were now able to carry more ammunition, (meaning 43 rounds - and later 46 rounds, with upgraded mags - versus the minimum 18 rounds required when revolvers were being carried). Okay, fine.
Then, there came a time when the 10-rd magazine/feeding device laws were happening at the fed and state level where I lived & worked (CA).
During that time I could still buy magazines that had higher than 10-rd capacities due to my LE status/exemption. Oddly enough, during that time I only bought 1 pistol for which higher than 10-rd capacity mags were available, and the "hi-cap" mags it used only held 12 rounds.
I still own that .40 pistol that uses 12-rd mags, but I also have a lot of 10-rd mags for it, just in case CA ever changes its laws to eliminate the 'pre-ban, grand fathered' exemption for private citizens and retired LE (they came close last year). It will be annoying if that happens, but the world won't stop turning.
All the rest of my collection of semiauto pistols I used to use for off-duty, and now for retirement CCW, have standard mag capacities of 6, 7, 8, 9 & 10-rds.
I still own & use several 5-shot snub revolvers, too.
In recent years we've seen the .380 ACP become the fastest growing and selling pistol caliber for non-LE/private citizen sales (according to the Glock instructor in my last armorer recert), and the gun companies have certainly been working to benefit from, and feed into, that popularity.
The demand for single stack 9's has been growing, as well, mostly meaning magazine capacities of 6-8 rounds. The demand for small compact/compact single stack .40's & .45's has also resulted in mag capacities of 5-7 rounds becoming "normal" and apparently acceptable, too.
I doubt the growing demand for smallish private citizen CCW & LE off-duty/secondary weapons is going to abate overnight.
Now, as a firearms instructor, I've often suspected that more than a few folks who carried hi-cap guns might be "kidding themselves" when it came to realistically evaluating their abilities, knowledge and skillset, and might be hoping "higher capacity" would somehow offset their shortcomings in those other areas.
Ditto some folks who promoted some particular caliber, or brand of ammo, as being "superior" to other choices.
Confidence in equipment (which includes "capacity" considerations) is all well and good, as long as it's justified, and doesn't distract needed attention from the user considerations.