Did I say “later this day”? I clearly meant “later the weekend”, obviously. 
You can find my question, here and read the answer of 2d20 developer @Modiphius-Nathan, here.
I concur with @betatester that ‘Vicious’ is a, well, vicious setting. Though I do not think that paying one minor action every round to get it, is too costly. That being said: If the gaming group is fine with house-ruling otherwise, I am not the one to complain. 
Regarding the in-world explanation: Reverting setting after a shot could be seen as built-in safety mechanism, as would be weapons-drill to change setting to default after a shot. There are plenty of ways.