Yeah, I suppose the dart throws are both too slow and too easy to do at the same time. Some enemies do move the trajectory of your darts, but not enough of them, probably. Maybe all of them should?
While it's true that shooting for the center might net you more runes than any other play, I've found that after a while you do need to cast certain spells - healing mostly - in order to keep on going. But you're right that you can just toss at the center and hope for the best.
Thanks for the comments :)