Firing through DNI, more advanced safety systems... If we assume for a second that some of the technological functions can ONLY work if that link is severed, then it makes sense that it would be.
And throwback guns don't need an explanation for being "immune" to bricking, because they're not. They don't have wireless, sure, but nothing stops you from plugging into it and bricking it over a wire. Gun H(e)aven 3 did include rules for a weapon property that could indicate such immunity (Vintage, I think), but that property ALSO makes it incompatible to other technological features.
Those do not require that the mechanical connection between the trigger and pin be severed. They only require additional elements to be added. DNI could easily use a system just like a feathertouch pad. The trigger still works fine, but when you engage the feather touch pad, it triggers the pad electronically. Fry the pad, the trigger still works fine. Advanced Safety just has to engage the "safety." Nothing about that involves breaking the mechanical connection between trigger and firing pin.
So, no, it still makes no sense. It is, as with many SR 5 things, designed illogically and horribly if the trigger no longer connects to the firing pin.
I too can only see downsides, but that is because I grew up in a world that uses this system. I'm sure when the Wheelock was invented, people who grew up with matchlock firearms did not trust them because there was no constant flame to ignite the powder, a flame that the matchlock provided.
Even today, military grade weapons are being developed to use both caseless ammunition and an electrical ignition for the caseless propellant. This system uses a computer to control the electrical ignition, and therefore the rate of fire. As Shadowrun has made it clear that caseless being commonly available, and caseless being more easily ignited electrically than physically, I find it to be believable that the majority, if not all guns would be made to that standard.
As for how long it would take for people to trust electric guns over mechanical, who knows, but when it's what you grow up with, you only see flaws in other systems... just as we only see flaws with electric guns.
It has nothing to do with growing up with our current system. It has to do with actually analyzing the system being proposed. There is a rule called the five year old rule (I believe the reference comes from the Evil Overlord list). If a five year old can spot the gaping flaw in the system, come up with a new system. This proposal fails the five year old test. Given, the five year old I know is smart for his age, but still.
Sure, people hated the wheelock system at first. The people that actually analyzed it thought it was a wonderful improvement. The opposite happens as well. People introduce new systems that are horrible, and after analysis they fall by the wayside. Take a look at pinfire ammunition. There is a reason it didn't ever become a real standard.
As for electrically fired ammunition, yes it exists today. Yes, some of the systems use a computer chip to control rate of fire. Almost all of them will still work if the CPU fries by pulling the trigger and sending a single pulse (the pulse is connected to the trigger and works even without the CPU).
I see many advantages to electric guns. Quieter, lighter ammunition, easier to clean, no ejection port. The only current downside is really the lack of a good heat sink, which causes ammunition to cook off if the fire rate gets to high, but they've made leaps and bounds in that field in the past decade. Many use systems more similar to plastique than traditional propellants. This is called analysis. I see no reason to disconnect the trigger from the firing mechanism though. All that does is promote failure as the CPU is usually the most fragile element in most electronic devices. Again, it's illogical and horrible design to cut out the most basic backup for a device.
