There is an assumption that once we are brain damaged, we cease to exist, and it's just taking out the trash, more or less, to get rid of the body.
It's wrong and immoral, but it's all over the culture right now.
Culture of death.
"Brain dead," no problem. I drove an ambulance for a living and completely understand that. No brain activity equals dead.
Brain damaged, however, means still alive.
Now, my brother in law was in a very nasty accident when he was a truck driver and ended up in a coma, then a "persistent vegitative state" for several months (he was unresponsive to external stimuli). With intensive theraby he got better, to the point that he is up and about. My sister didn't know him when all this happened, so he obviously is doing pretty good. His condition is similar to someone who has had a medium stroke. Some speech and cognitive impairment, some difficulty walking (but that's more from hip damage than brain damage). He gave me a video several years ago that laid down some good background.
One thing about him, however. He's made it very clear that he doesn't want to go through anything even remotely close to what happened before. He refuses to wear seat belts and he carries a living will (with DNR in big block letters) wherever he goes.