If you give all classes aoe standard attacks, there goes the uniqueness you were speaking about, now they are all the same... bad idea.

Lancer has a standard attack purchased with guild marks that hits monsters between you and your target
Marauder has a standard attack purchased with guild marks that hits enemies in a cone before you

The above are examples of why the classes are unique as they are.

Don't fix what aint broken.

All classes with AoE? All set thanks.