If it's an NPC, their first reaction is, 'can I kill it?'
You should just ~roleplay~ that your dog can die. Problem solved.
Problem is that the dog is melee only, this matches very badly with an sniper build who take out enemies from long distance, for hard fights you put down mines infront of you position and prepares to redraw to secondary positions.
You have an high dsp close range weapons like an machine pistol or shotgun for close work but this would be useless if the dog run inside an enemy camp.
you could kill companions in hardcoe-mode
unkillable companions really svck, unkillable anything really svcks, beth should stop adding essential tags and start adding better AI. companions should really get a tactics menu like in dragon age origins, tell them (or in the dog's case, train it) to avoid running off more than a couple of feet, make them target melee enemies or ranged enemies, ect.
Hopefully it is in. Otherwise it'll be a quick GECK fix to solve this idiotic issue. Things die; Fallout is no exception.
Interesting because I purchased The Elder Scrolls IV: Oblivion in 2006 and I made a mod that lets all NPC's be killable and I still play The Elder Scrolls IV: Oblivion to this day today still and since 2006 to this day today I only had 2 of those NPC's that were essential die.
This is one of those gameplay enjoyment vs. immersive enjoyment things. I can see why all things should die, and why it's disturbing when they can't. However I never take companions purely because I don't like baby sitting stupid AI. In fact I don't think I've ever used a companion for long in any of Bethesda's games.
I like the option to decide how you want this particular thing to go like in New Vegas. I don't want killable companions, it's tedious looking after them for me, but if you want that risk - reward mechanic then more power to you!
Doesn't seem to be pushing the dog on you at all.. One of the options is "get out of here" (or something to that effect.) Pretty sure all companions will be able to die just like in all the other games.
But they had also scaled back the radiant A.I by that point.
The issue with the radiant A.I as it was originally was that a character might get hungry, and head for the nearest food. The intention I think was they'd buy it or get it from home, but they were more likely to steal it. And do a bad job of stealing. They'd get a attacked by a guard, someone else would join in on one side or the other, and before you know it, mass brawl.
As a result they did have to scale it back a lot and result to more scripting, which was way many characters followed pretty precise routines.
They solved the problem in Oblivion by dialing back the AI, the essential tag was no longer necessary. (did you see anyone stealing bread, and getting arrested?)
One of the reasons that ISN'T advertised by beth for the the essential tag was.... Players. I remember dozens of threads in the Morrowind forum that started out: "I killed x NPC, now I can't complete his quest, how do I fix......."
Lots of cat-people here. Not that I'm complaining...
It's abysmal they made essential NPCs just because of those people. Protected NPCs are a good choice. Essential is not.
To be fair, I'll be the first to admit there were times I'd fire up Morrowind and just go on a Rockstar-inspired Kill-a-Thon to vent steam.
It's just all too often, people would do that and then save their game and realize along the way, they'd broken a critical quest.
I'm all for turning off essential flags, but especially in Fallout...Canine Companions need to have an extra layer of protection. Admittedly, having the dog gunned down within seconds of the firefight starting is very realistic...but it's also not very fun. Bad enough I'd already lost ED-E...now I'm not sure I even want Rex.