[Question] How are the NS pistols not a straight-up upgrade?

So, the NS systems pistols are 6 magazine pistols that hit super hard. Higby said "well if you want a pistol to switch to to just get a few shots off, this is a great choice" or some such. But isn't that how we all use pistols the majority of the time?

Maybe I'm missing something but I take out my pistol in 3 situations:

1. I've run my clip empty on my main weapon, am alive, and need to finish off an opponent.
2. I'm alone, way far from home, and totally out of ammo on my main weapon.
3. I'm killing a spawn beacon. No need to waste main ammo on that.

Of these scenarios, 1 is by far the most common and critical. So since the NS pistols should excel at finishing off wounded foes, why would anyone use anything else? Isn't this liable to be a huge upgrade, across the board?

That being said, I'm a proper VS zealot, so I don't use common pool where I can avoid it. I'll be keeping my Manticore... but that's not a rational reason. Is there any rational reason not to use the new NS pistols?