the developers were designing Fallout 4 to be a game about cooperation, teamwork and relationships. They want you to be able to build these long-lasting trust relationships quickly, and to have those characters permanently die off would undermine the very goals of the game's message.
How thick can you be not to see that?
Hey did you know you can build long-lasting trust relationships with your companions in New Vegas? Some of them even had their own quests, some of them had their own hidden quests. Some of them told you about their backstories. Some of them can only trust you after you do a specific thing.
Having them able to die makes their deaths much more tragic after going through their backstories.
How thick are you to not notice this?
You stop caring about your companion's well being after they "die" like 535443543 times and gets back up later in 5 minutes in fallout 4. It starts getting old as forget. At this point now they are just wasting your stimpacks because they don't need them. They'll never die. They'll eventually just become meat shields because they have a valuable skill, not being able to die. I've had companions become shields for those Self Delete super mutants. It starts making me think less of my companions as equals and more of just shields.
