Yes the writers are abusing this privilage but it's better than not be allowed to use it at all.
I disagree.
While tension may suffer if you know that the characters aren't going to die, I think it suffers just as much when you know that most of them are going to die. In both cases, you already know. The only real difference is that the first lacks tension and is depressing to the point that I just don't care anymore, whereas the latter lacks tension but can make up for it by being fun and entertaining.
"Death as source of tension" only works when it's used sparingly. If it is abused, I really do think that it becomes much worse than "no deaths at all" .