One thing to remember is that anyone can take the Ritual Caster feat and pick up the Raise Dead ritual. As such, it's supposed to be a bit of a last resort, and probably something that the party can find as a service in large cities and such. It has a penalty involved because it's a common means that anyone can employ with the right training. Kind of like how the Heal skill allows you to grant things like a saving throw, but at a much higher cost than some of the Leader powers specifically designed to allow such things.
Powers, on the other hand, are very different and require specific class, power and/or Epic Destiny selections. These have no penalty because it's a Cleric's job to have powers like Revive, in order to save the party's bacon. He can only do it once per day, but as long as he's alive he can save someone. Granted, if the Cleric drops....well, that's what Raise Dead is for!