Just because the skill looks amazing on paper does not actually mean it is. Musketeer and Cannoneer skills suffer from long animation times and are single hit aside from Covering Fire. When you hit damage cap with them, you have absolutely no way to ever increase their potential afterwards.
In actual practice, they’re not amazing DPS skills which is what matters when you’re contesting 280+ world bosses or doing other content where sustained damage matters.
With a 2s animation time + 25s cooldown and a 100k damage cap (easily reachable), snipe amounts to 3703 DPS and that’s the highest it can ever reach.
When you are considering skills to fit within your rotation then you may realize that other classes at lower ranks can output similar DPS and even exceed that without being hindered by the hard cap on damage dealt. Fletcher, Wugushi and Sapper come to mind because of their fire-and-forget abilities which lets them weave other skills into the rotation.