It's a delicate balancing act, in my opinion. GoT and Breaking Bad are interesting and all, but they work as much on shock value as well as anything else. Is this the path that Star Trek should take?False eqivalent. There have been approximately 50 hours of Bond, 700+ hours of Trek. But even granting your premise, there was a major character death as recently as 2 movies ago in Skyfall. Then there is the death of Felix Leiter, Vesper Lynd, Bond's wife, etc. They obviously can't kill the lead, but Bond has not been above using a character death to heighten dramatic tension.
NCIS (who killed a lead in Season 2, btw) viewership's median age is 61 and Criminal Minds is 56, people who are accustomed to a different type of storytelling. These are not the viewers I think CBS All Access is gunning for. Titanic? We DIDN'T know how it turned out for Jack and Rose, one of whom dies while the other lives.
If this type of storytelling isn't your bag, no harm no foul. It is the type of storytelling that I would bet the brass at All Access are going for. Younger viewers who are watching Justified, Breaking Bad, Man Men, The Walking Dead, GoT, at least in my opinion
As I said, death is unavoidable, but in fiction, it isn't always necessary. If it is done well, serves the story, and provides character development then I can get behind it. "Random death" (trademark pending) is not interesting to me.
As a side note, NCIS killed two main characters (Kate in Season 2, another Season 5). But, the rest, GIbbs, Dinozzo, Ziva, and McGee, all survive. The larger point being that NCIS uses death in different ways for main characters, and is still quite entertaining.