Have you guys ever counted how many times you are in a bunker on your typical round of golf?
For me it's maybe two or three, even on heavily bunkered courses. Most of my bad shots finish well away from the bunkers.
The effect of bunkers is 80% psychological ... getting players to aim away from the trouble, or sucking them in. Obviously, their effect would go way up if bunkers were not raked ... and then we wouldn't build so many extraneous bunkers, just the ones that really mattered.