Now, I'm new to Shadowrun, and I will totally admit that this might be just me, so take it as you will.
Yes if you get caught without armor a ganger with a pistol should be able to kill you and even with armor a ganger with a pistol can kill you. But I don't tend to have gangers just jump you for no reason. notice the gangers in the tattoo shop they are there and they don't even say a word to you, because you don't look like marks, you didn't try to provoke them, and you aren't worth the trouble because a skilled guy with a gun can kill them as well.
This actually sounds... MORE unrealistic and lacking in grit to me. I kind of imagine real fights where you're dragging yourself out of fights all bloodied up and bruised, because brutality and stuff. It's not that a ganger CAN kill us with a surprise shot from the dark. It's that there's a very, very good chance that he WILL kill us in a single shot. I mean, if I was surprised, and hit, and that ganger got... 3 or 4 hits on his attack, Crow would be dead before he even hit the ground. Human beings are actually remarkably durable, we can take quite a lot of punishment without dying, and heal in a way that is almost bizarrely rare in nature.
But anyway, I'm not trying to rock the boat, the statement just made me raise an eyebrow. I just know that, as I crunch math in my head with the play style that it will probably be kind of common to not wear full-body armor in the course of our missions for obvious reasons, that I'll probably end up playing in an extremely risk averse fashion, since any amount of firepower has the not insignificant chance of just dropping any one of us.
I'm not arguing to change the rule if you don't want to, math crunching in games is just kind of an impulse of mine. Comes from all my years of character building and optimization as a hobby.