As I understand it a good deal of rangers bypass this trait for flashy shot. Call me a noob or flame me if you wish but i don't see any reason not to have this trait merited.
Based of the rate that rangers consume ammo and after seeing all the post about ammo shortages/attainability I cant see why more people don't use it.
The way I see it snapshot is a given but why flashy shot? It has a long recast timer and enmity+ just for more damage in a single shot. I don't consider this a very good trade off vs free ammo