40 hours into the game and I disagree with the topic's title. Warriors not only have excellent crowd control (being able to knock enemies down) but can increase their damage with the rage skill. My warrior can do around 500 damage in total with an ordinary strike, meanwhile his buffing skills and knock down abilities actually makes him the guy who is essential to my group's success. Magic is all well and fine but the fireball does less damage than a whirlwind attack I find.
People forget this is a party based game though. The wizard is more versatile (thanks to being able to have a crap load of spells and elemental magic) but has less health and defense than the warrior who can tank and withstand attacks. The idea is that classes are meant to complement one another and most often in RPG's, the wizard by late game, has so many spells to use as opposed to the abilities of the other classes.
Optionally, just mix and match skills instead of going for a pure mage or warrior. I've given my warrior some magic spells which can stun the enemy or weaken them. My ranger has the charm skill, an archer skill which is OP if you ask me (as it can turn powerful foes against their allies or just allow your group to wail against them - if they're the last guy standing - without them doing anything for three rounds and when it runs out, I've got two warriors who can perform the knock down fist attack). I find myself without a magic companion because these other abilities can just as well incapacitate a whole group.
