Wizards have access to 2 very similar spells: Shield and Mage Armor Both provide you with AC +4 Bonus, but Mage Armor has Range touch (i.e. you can cast it on other party members) and Duration 1 hour/level, while Shield has Range personal and duration 1 min./level
From my point of view Mage Armor is far superior to Shield. In my party Wizard and Monk formed mighty combo, where monk got +4 AC bonus for free every fight. It looks like a gamebreaker.
Question: Why are these spells, which seem so similar in effect, so different in range and duration? Are there any drawbacks or advantages to one spell or the other which I didn't see?