Writers generally write plots in order to take a character from point a to point b. For instance, for Buck's bisexual discovery episode, rather than thinking "I'm going to have Buck meet this hot pilot and see what happens", Tim probably thought "I want Buck to come out as bisexual. How do I believably do that?"
People keep saying that if 911 is going to move forward, it needs to start bringing on new blood and integrating it into the cast. Well, this season, Ravi has been spotlighted multiple times. But in order to bring on someone new, someone else has to leave or fall back a bit. Technically, Tim could move one of the younger characters to another shift, but I doubt any of the younger actors want their screentime cut. However, Peter has stated that he's not into doing all the stunts anymore (and he looked super miserable shivering under a towel shooting the cruise line story) and that he might want to spend less time shooting generally. After all, he's getting a nice, fat producer cut now. He could probably shoot part-time and still make the kind of money he wants, and that would free up some budget for another character.
Additionally, unlike all of the other characters, Bobby has options that would keep him within the world of the firefam and would give 911 the opportunity to explore new parts of the first responder world. He is senior enough to run or be nominated for a senior position in LAFD, one that operates more behind the scenes, structuring budgets, communicating with news outlets, creating trainings, etc. That's a whole new world for the show. It keeps Bobby in the mix enough that we could occassionally see him show up at the firehouse for dinner, but creates a much less demanding shooting schedule for Peter.
But Bobby would never go for that. He would have to retire and then get bored. So, the question becomes "How do we take Bobby from gung-ho fire captain to someone who voluntarily gives up his post?" After all, s7 ended with him finding new energy for the job. A near-death experience like the one with the car pile-up wouldn't cut it. Because Bobby has faced those multiple times over the course of the series and hasn't considered giving up. It just wouldn't be believable to the audience and wouldn't be dramatic enough to cause the kind of shake-up that Tim wants to do. So, what would be?
Well. What if Bobby and everyone Bobby loves had to think he was dead for multiple days? What if the audience had to think that? What if viewers and the firefam had to watch Athena and her children (including Clifford) grieve him? If Bobby came back after something like that, absolutely, both the audience and the firefam would buy his wanting to finally retire. Especially if you throw a dream house into the mix? And Bobby suddenly desperately wanting to live as he's dying? Folks may end up messaging Tim on Facebook demanding that Bobby retire RIGHT THE FUCK NOW.
So. That's just some food for thought as to why Tim might do a death and resurrection. Additionally, whenever any character has a drawn out near-death experience it gives the writers permission to make big character shifts very quickly as characters process their grief. Characters are allowed to look at their lives, realize tomorrow is not promised, and choose things they may not have before the death. Those changes are even more believable if the audience has to mourn the character who almost dies with the characters experiencing a shift. So. You know. If, say, the show was going to have a character, I don't know, recontextualize his relationship with his best male friend and realize that choosing him would be choosing joy? Or if another character who had never stood up for a leadership position before were to suddenly want to do that? A major death that the audience felt alongside those characters might ease those transitions.
Think about it.
