The Crimson Binome
Hero
Spellcasters need Dexterity and Constitution at least as much as a Strength-based fighter does. Initiative and HP are useful to everyone, and while the fighter is going to be the target of more weapon attacks, their higher AC and Hit Dice combine to make those stats no more useful over-all than they are to a wizard.These kinds of trade-offs basically don't happen for spellcasters. You pump your core stat as high as it will go...and that's that. It gives you everything: the DC of your effects, bonus prepared spells (if applicable), the magnitude of ability-dependent effects.
A fighter can get by with just Strength exactly as well as a wizard can get by with just Intelligence.