For the reason that it has more redundant safety features than any of the other striker fire that I know of. Its everything a Glock and all of their copy's want to be, but aren't. Ive posted that I own a Taurus G3C pistol, I own one because its a micro that comes with a manual safety.
Spend 26 min and watch this video, it breaks the 320 fire control group down.
Where did you see that Glock and others want to be like a P320?
None of my striker fired pistols have ever discharged without me pulling the trigger and I don't have any Sigs. Even when dropped, they don't go off.
Sounds like you prefer a pistol with a safety, not everyone one does. Personally, I like mine ready to go when I need them, without a manual safety.