It would be better if they fell on the floor, like when people die. But then an hour or two later they get up, instead of 10 seconds. They made to many people immortal though, if someone kills someone else who gives a quest then its their fault.
Or even making "reincarnation" a real spell, not a short-term excuse for a "summon-dead".
Sure it should be expensive as hell, with reprocusions... But still possible. Poof, problem solved. (Can't tell you how-many time I have used ressurect on all the idiot towns-people who are not AI smart enough to run away from danger, heading inside a house for cover. Just so I could sell them items, or complete a quest they are part of. That was the only good advantage of the game forgetting to remove all the dead bodies in towns.)
If you need to justify it in the game... make it part of "The fate of the gods. They choose who can and can't be resurrected." (When tried to ressurect... fails scripted as this... "The gods refuse to return the soul to this body. His/her passage has been set in stone. This body should be mourned and respectfully rested."
Anything except conflicting immortality. Heck, make that a mini-quest... "The voice of the Gods calls to you. Take Hadvar to the ressurection alter."
The reason many are immortal, is because of the crazy need to have them mentioned in recorded dialouge. "Go see my mother Frita. She knows more about this." (So Frita has to be immortal, so she can be there.) As opposed to saying... "Yes, I think I remember someon saying something about that." (Quest updates with "See {Name-here} to get more information.")