Divinations don't ruin games ime, they simply change the types of adventures that the dm can run. A good murder mystery is hard to pull off when the cleric can commune and say, "Whodunnit?" Even so, it's possible- the answer might lead to the murderer, but not who hired him. Layers upon layers... One key to being a good dm when it comes to these things is to design situations where the pcs need divinations (or flying, or teleportation, or whatever other game-changing power you're talking about) to get through. A high-level mystery might have no clues to begin with; the pcs must ferret them out with divinations of whatever sort (ah, thought capture, I miss you). In a good high or epic-level 3e adventure, the pcs should face challenges that they have to fly to deal with, teleport or plane shift to get to or away from, discover information with no ordinary source, etc.