I think if one was going to write a book on death they would need to include many alternatives for locations for dead characters to exist in. Jetting off to a dead plane is all fine and well, but as you say it dosnt keep the game very togeather.
Im not sure if any forthcoming releases are covering aspects to death that would keep games togeather.
Lets see, how many ways can you think of that a PC could die and still exist in the current game in some shape or form?
Spirit - embeded inside some opject, weapon etc. that speaks/communicates with the rest of the party.
Animals - the spirit of a dead PC could enter his/her old animal companion or any other unfortunate beast and continue to exist in that form
Imagine rules for animal rebirth where the characters alignment (and level) upon death determined what kind of creature they came back as
Then we have of cor(p)se, the undead. But perhaps a rather religios PC would become a different breed of undead, one with etiquette
At first glace death seems quite limited...very much the end. But once you explore it can be taken quite a long way