Raise dead didn't make anyone immortal, you could never bring someone back who'd died of old age.
What changing the profile of raise dead does is cause some significant changes in both what PCs, and bad guys can do. Particularly PCs can't raise the dead to use as a witness, bring back victims of assassination back from the dead (a very important function of the spell), bring back an emeny minion dominate him and use him to get at his master, and so forth.
Restricting the availibity of the spell also makes little logical sense in game, why can only certain people be raised? Why are PCs so special?
It's just an option restriction that seems unnecessary. It was always easily within the DM's power in previous editions to restrict who could or could not be raised (his spirit refuses to return from the realms beyond, deal with it) so this seems another completely unnecessary 4e change.
I guess I'm an idiot.
I love the fact that very wealthy people no longer effectively are immortal.