Eccles said:
What's wrong with the 9th level cleric merely being extremely fat, lazy and ill-tempered? (Possibly even corrupt).
Villager: "Ogres are attacking the farmsteads!"
Cleric: "I can't be bothered. You deal with it."
I know this approach incensed my players at one stage, but it did make sense for the cleric!
Not to mention Lawfully Cowardly.
Dogbrain said:
Not at all true. The difference between D&D and many other systems is that in D&D, a single 9th level character is equivalent to seventeen divisions and a support company of "starting" player characters. Perhaps not that much, but the disparity is enormous.
Methinks you overstate your case a mite (especially if bows are involved

), but your point is taken, to a degree.
However, there are plenty of reasons why a 9th level monk and 9th level cleric wouldn't go out and stop a bunch of kobolds and their BBEG. Not the least of which is the all-important concept, already mentioned, that they can't be everywhere at once, and they have duties.
Consider: I'm the 9th-level head abbot of the temple of the Sweeping Hand. I am responsible (I'm lawful, remember) for the care and training of 40 other monks. I need to safeguard the temples sacred scrolls, which contain the ancient knowledge of my order, including the dreaded Poison Soul Fist. I must lead each day's meditation, provide instruction, see to both the spiritual and operational requirements of the temple each day. I
could go hunting those kobolds and their chief...on their home ground, away from my temple, foregoing my duties and leaving my monastery unguarded, all on the assumption that I'll be able to find the BBEG. Or I could task some young acolytes who show promise with the task.
Consider: I'm the head priest of the temple of Rao. I serve the god of Peace and thoughtful consideration. I have led a quiet life, and I safeguard the village. The people of the village look to me for spiritual guidance, and I have few skills in combat, especially in my older days. I am the only person in my order powerful enough and blessed enough to summon the power to revive the dead....dare I be foolhardy enough to risk myself in such a situation? What if I am slain, waylaid or even delayed, and prevented from helping some of my devout followers? What if someone died while I was away, and I returned to late to help them? I have many duties to the church that need fulfilling. There are daily temple duties, care of the flock, advising the town council and the local lord, and remaining ever vigilant against the kobolds and other threats. What if the local brigands learn that I've left the village, and decide to attack while I'm gone? What if I go the caves to find the BBEG and discover that it was a trap, and he's lead an attack on the village to plunder and burn, and then escape again?
There are many, many reasons why high-level NPCs might not participate in such an exercise. Even in a game where PCs never gain a great deal more combat prowess than they have at the beginning of the careers, such as in GURPS, there is still a question of Why Me? In a game where the players works for a large organization, there will be more powerful, better equipped and better connected people. And the question will rise again: why send me instead of twenty cyborgs? Why do I go, instead of Elmo the Assassain, who's better trained? Answering those questions, or changing the question itself, is the DM's job.