Divine casters (clerics, druids, paladins) get their powers for a reason. If they aren't spending a majority of their time advancing the agenda of their deity/spirit/whatever, then their powers will be revoked.
This does not apply to pacted casters (for example, warlocks).
The gods feel that raising the dead is a special reward for those who have done (or will do) great deeds that advance the interests of the god. Divine magic to raise the dead will fail to work if the target has not done deeds in service of the deity or is not a strong ally of those who have.
This is why death and plague still stalk the lands. A farmer dies of the plague? A sailor is killed in an accident at sea? Tragic, yes. Worthy of raising from the dead, no.