Something I think at least certain spells need, for instance, Ibans Blast cannot be autocasted, Neither can Sara Strike, Zammy Flames or Guthix Claws (excluding SoL and SotD). There are others aswell that dont sit in the regular spell book's auto cast screen. It would work by right clicking said spell in the spell book and toggling and auto cast option. It is really annoying having to manually use certain spells, ALL the time. Especially comparing it to other attack styles, mage just comes off worse (unless your using ancients.)
I think doing so will add more variety to players rather than the same style repeated.