Hmm. Interesting question.
Often, death on TV shows occur for two reasons. One, they kill off the character for shock value (or contract dispute with the actor), or the actual actor or actress dies, and the character is killed off as well, to explain them no longer being on the show (John Ritter, for example).
I think more people die on TV shows for creative reasons than any of that backstage nonsense. HBO dramas are a great example. When people are killed off of True Blood, Game of Thrones, Boardwalk Empire, The Sopranos, Oz, etc, it's so those deaths can be used to further the story. Daenerys Targaryen can be the ultimate face in Game of Thrones, but if the story demands it, they can have someone kill her to create an ultimate heel.
WWE doesn't do that though. Instead, when they're done building up a top face, they shove him down to the midcard, and have him soil the good-will he drummed up during his top run. This might be a morbid example, but let's use Chris Benoit. He became World Champion. He defeated Triple H. He was on top of the world. But it's push was ending, there was nothing more to do with the character. Why not have T kill him off? It would have been huge. Benoit would go out while on top, it would create a top heel, and a new hero could be built up to fend him off.
Or better yet, let's talk about the bad guys. Once Cena is done with Umaga, what's the point of keeping him around? Everyone knows Umaga's undefeated streak was leading to Cena taking him down. There was little left for Umaga to accomplish in the company before he was released years later.
My point is, sometimes you should just get rid of guys because they are no longer required. In present day WWE, I don't see any point as to keeping Alberto Del Rio around. It would have made sense to me if some bigger bad guy would have killed him off to build up his notoriety (Brock Lesnar, Rusev, etc.). Alberto was a top-level performer and his character was had personality and clear goals in mind. By not killing him off, they just throw him in the midcard where he waits out until the day he is released.
They just fired Drew McIntyre and Jinder Mahal for budgetary reasons. Imagine if Rusev had killed them and Heath Slater was the sole survivor of the slaughter? It would have added dimensions to both those characters, and made Heath a sympathetic character to root for.
Of course, in PG-WWE, "killing off" might be out of the question. But WWE has done stretcher-jobs to symbolize getting killed off before (like Sheamus ending Jamie Noble's career). Everything I have mentioned can easily be substituted for having those people written off as careers ended.
If we had characters being written off regularly, WWE would be a much more suspenseful environment. Instead, guys who are written off are just guys who have contract disputes and retirements. It's never used as a creative tool.
It would only work if you kill off the "gimmick" and repackage the superstar as a completely new character, or different look (e.g. ABA Undertaker was "Buried Alive", but came back as "Deadman" Undertaker). Taker is meant to be a zombie character, so he can come "back to life". The Undertaker is the only official "undead" wrestler in WWE history. Undertaker comes back from the dead more often than Stefano, (a character from "Days Of Our Lives". I watch too much of that show).
Yeah that's why I mentioned Undertaker. He's always being buried alive, but everyone knows that he's coming back so they are okay with the apparent on-screen death. Paul Bearer being suffocated in cement was hardcore though.
Now, real-life deaths are mentioned on air. Owen Hart and Eddie Guerrero were "written out" by their actual deaths, but was done with a tribute show. I don't think you could write it that they are killed by another wrestler, as it would be tacky.
I'm a firm believer that you shouldn't kill off the character of someone who died in real life. I thought John Ritter's death on 8 Simple Rules was tacky. It felt like they were just trying to continue the show as a cash-grab, using his death as a marketing tool. Chris Nolan didn't acknowledge Joker's fate in The Dark Knight Rises due to the same principle and I applause him for it. WWE shouldn't kill off anyone who is killed in real life.
That being said, it's fine with acknowledging their real-life deaths and paying tribute, because they're pretty much breaking kayfabe at that point. It's like if Steve Buscemi passed away in real life, and HBO aired a tribute special with the cast in the middle of Boardwalk Empire's final season. No harm done.
If Vince wanted to be mischevious, he could have killed off Fake Diesel and Fake Razor Ramon, as a proverbial finger to Nash and Hall for leaving for WCW.
That's actually a great idea. He should have done it. Those characters never appeared on TV again (Diesel's 2011 appearance in the Royal Rumble notwithstanding- he came back as Kevin Nash shortly thereafter).