Pretty much what distantvoice said.
Most of the wizard apologists are the more immature players that just play to win and say "Well just spread your army out!" because they don't want to admit they are basically ruining the FUN of a pvp fight.
Should there be wizards? Yep sure
Should they be able to solo armies with one or two spells? NO they shouldn't.
They should be able to kill a battalion or two with a spell sure, but not whole damn armies.