If you ask "which class is best at X?" clerics finish second in about 5 or 6 catagories. The only one they win is healing (maybe a tie in divination). On paper this may seem unbalaced, but I have never had a cleric become the standout badonkey of a party, even with the whole Harm thing. This seems to be party because healing benefits the whole party rather than the cleric and being second in many categories doesn't make you a badonkey, and partly because you have to try to become the party standout, and such folks seem to gravitate away from cleric. On paper, a group with 3 marshal cleric and no fighter might do better in combat than a group with a figher, and mage, and a cleric; but a player who takes a figher or mage over a cleric can deal out damage much faster, and therefore seem more fearsome and therefore a more attractive choice.
In (US) football terms, magi are the quarterbacks, fighters are the running backs, and clerics are the offensive line. Having a good line may be the most important factor, but if there were an NFL roleplaying game, folks wouldn't be clamoring to play linemen. In terms of party compostion and overall sucess, cleric may well be unbalanced, but in any given combat, they are if anything slightly underpowered (along with other classes who have lots of non-combat abilities like rogues and rangers).
In (US) football terms, magi are the quarterbacks, fighters are the running backs, and clerics are the offensive line. Having a good line may be the most important factor, but if there were an NFL roleplaying game, folks wouldn't be clamoring to play linemen. In terms of party compostion and overall sucess, cleric may well be unbalanced, but in any given combat, they are if anything slightly underpowered (along with other classes who have lots of non-combat abilities like rogues and rangers).