Having AOE not do friendly-fire damage would make them too powerful. The ability to drop one (or two or three) right on top of yourself would just destroy all your foes. You would never have to use any other ability.
Concerning AoE. There are a number of different types of AoE, not all of them are line of sight. What this means is spells such as inferno, you can open a door so you can see within the room, then go to a different part of the room you are in and cast through the walls.Also spells like Blood Wound do not affect your party. Blood Wound + Inferno + Fireball was one of my favourite combinations.On the topic of friendly fire later in the game I grew tired of the agro take from AoE spells and so tended to use a couple first level spells (cone of fire, cold shock [a must have IMO] and arcane missile), though concerning friendly fire I normally didnt mind hitting my team mates too much in short combats. I did however get generally annoyed at how many of my spells I could not use in the more difficult combats due to FF.
On the console version, AoE does no friendly-fire damage on normal and easy difficulties, and only half damage on hard. I bumped my difficulty up to hard because I wanted there to be some consequence for dumping an AoE spell on top of my team. I would rather play on normal difficulty with full friendly fire, but that is not an option.
If you rolled a mage in Dragon Age: Origins, you're probably used to timing your spells perfectly to ensure your comrades don't get caught up in the hellfire you're about to summon. There was nothing worse than preparing to spray your enemies with Cone of Cold, only for your main DPS character to charge into the fight and get themselves ice-cubed. It was frustrating, but it forced you to become a highly tactical player, and soon became one of the main pulls of the game. For some reason, Dragon Age 2 only offers friendly fire on the Nightmare difficulty, which kind of lives up to its name. If you want to experience the tactical combat of Origins without breaking a few keyboards out of frustration, you need the Friendly Fire mod . 153554b96e