You really want chargeable, directional spells in an environment that demands almost constant movement? That is like, counter-intuitive. Having to face your target to shoot a spell while you move away from him to do mechanics would be SO bad.
And having to pay attention to charges of chargeable spells when the fights are more complex also counters your argument. It is the opposite of what you said, having these casting features more common would work much better in early days of WoW, when fight mechanics were simpler.