Whoever designed casting range having minimum range had amazing foresight or just plain luck.
Giving spells no minimum range gives casters an amazing jail free card . Aoe spells dont punish single entity and only hurt multi units making casters a permanent bait.
They should be punished if they are left alone, so they need to be protected or kept at a distance.
CA, if you want these aoe spells to be useful. Make bombardment spells casting time faster by a second since they have to fall from the sky.
Vortex spells need to be cheaper WOM or better control.
This would also help against corner camping, box or forest box. Its one rock two birds.
For SP, just get another caster and drop it ontop of your surrounded caster