If it ain't broken, don't fix it...
Take your own advice. Sure the drives run hot, but the factory deals with these things. In most cases, you won't have a problem, unless you have no airflow through your chassis. If you really think that cooling is necessary, try one of the hard drive coolers available from Xoxide:
I used the 3-fan cooler for a while, until i realized i didn't need it and swapped it for the 4-port rheobus....anyways, the AOC is the best choice, because it actively draws the heat away from the hard drive before the air passes over it. The others just pass air over the drive.
If you have a fat wallet, you could consider a water-cooling system. The Hard drive cooler itself will run you about $35, and the rest of the cooling system will run about $250-$260.
Unless you **** money, go for the AOC.