Maybe this is the wrong place for this, but I don't know where the proper channels would be.
I'd suggest, in the few months remaining before launch, that Bethesda at least attempt to make the dog killable in Fallout 4. I have a feeling there are some quests that require him since they are really pushing the dog relationship it looks like, but (of course) I don't know this for sure. If this is the case they should, at the very least, make is so the dog can be injured to the point of being completely incapacitated and needing to go back to your base thing (which they are also pushing) to be fixed up.
I seem to be alone in thinking that the dog should be able to die, so maybe this should just be a slider option at the menu to turn this on and off, or maybe only make it a feature in harder difficulties.
Here is my rationale for why I think it should be this way:
Nothing makes me devalue a relationship faster than having one of the parties be completely indestructible. Why is this? Well it's a little obvious, it is because, at that point, you don't have to worry AT ALL about your partner. Really, how many times have you been playing games with un-killable NPCs and gone "eh, [censored] it. They can't die they'll be fine." When you remove the concern, you remove the connection that is supposed to be there too.
Part of the fun of having Dogmeat in Fallout, fallout 2, and fallout 3 was that he COULD die. Getting through the game with him alive was a feat, it let you connect with him, it let you worry about his well being, it forced us to load games hours back in order to keep him alive. What if you never had to worry about him in Fallout 3? Would you REALLY have connected with him in the same way? Really, there wasn't even much of a character or interaction between them for you to get attached/connected to. The only reason we did so was because we had to worry about him in combat and, every time you came out the other side together and alive, you felt a little more attached because you actually did something together. Dogmeats mortality is what made him lovable; if you could have thrown him into combat and KNOWN he would come out fine every single time we wouldn't have given a d**n about him, other than to have him thin down packs of enemies (which would make him a tool and joke more than a loveable character).
Take, for example, the Witcher 3 and Red Dead Redemption. Neither one of these games stressed the relationship with the horse, really. In fact, Gerelt pretty much admits he doesn't care at all about his horse. But, while both games have horses, and don't stress the relationship, only one game lead you to be even remotely attached to your horse and that one was Red Dead. Nothing made me devalue my horse in Witcher 3 more than the fact I could not kill it. I could run it off a cliff, stab it, leave it in the middle of combat, and no matter what it'd be fine. This leads to a Devil-may-care attitude when it comes to the horse and exploration. The only thing that made you like your horse in Red Dead was the fact that you could be stranded out in the wilderness should it die in combat or due to your negligence running it off a cliff.
Tl;dr - Mortality increases affection. Make the dog killable in Fallout 4, at least as an option.