Pathfinder/3X So How about all casters are highly specialized

Just a notion that occurred to me. It might be fun to ban the generalist casters like Wizard, Druid and Cleric and allow only the highly focused caster classes.

The list would be limited to the Pathfinder Summoner and the four 3x classes, Healer, Dread Necromancer, Beguiler and War Mage.

This would provide nearly the ultimate in niche protection for casters and give the game a very distinct "powers" flavor.

What say you all?