Two reasons actually. First, the .380 is much better with today's ammo, but it's still a very small cartridge, and not in the same league as the larger three you referenced. Secondly, 9mm ammo (practice or carry) is much easier to locate.
In a skinny sub-compact, I think the 9mm is the balancing point for power, control, capacity and gun longevity. Just my .02c.
I love my G42, but will pick up a G43 as soon as possible due to the cost/availability of 9mm ammo vs .380. The G42 won't be going anywhere.
I certainly agree with your comments on the G-42/43. I do hope the G-43 is a bit more accurate than my G-42. The G-42 does not group as well as my G-27/26 or G-19. It shoots about as well as my PF-9 which isn't terrible.
Some reports indicate the G-43's shoot well.
I just got a G-43 today found an IWB holster and ordered Tru Glo's for it.
I will be shooting it Monday morning with a view to comparing it to my G-19, G-27/26 and G-42.
Hopefully, Ghost will have a Plus 2 mag base and spring kit out for the G-43 soon. I really like theres on my
G-42,especially as a spare mag. There are a couple of extension bases , +1's and +2's available now but they use the stock spring. Until someone tests them positively I see no reason to try them.