User blog comment:JmLyan/Arana, the Lotus Archer/@comment-24526576-20140214202716/@comment-7481207-20140215091112

Good points, although spammable damaging ability doesn't always have to be on Q (Ashe for example).

Making Mystical Focus like Ashe's innate would make it too abusable and allow you to get free full damage shots when walking into lane/ganking/pre-team fight etc.