Putting points into focused aim hurts your dps by a lot. Also for hit with enchants that are not the bow, a hunter is trading agi for hit. Agi is the 2nd most important stat for a hunter, most important after they hit the hit cap. All gems that a hunter has to have hit to reach the cap is also at the cost of AGI.
If there was a 30 AGI scope I would agree with your rational of the hit cap, but trading hit for crit allow a hunter to not waste 30 agi they would have to either enchant their gloves/boots to get, or not socket an agi gem cause they needed to use a hit gem to reach the cap.
The only thing that is worse for dps than trading agi for hit (with the other enchant/gems) is trading talent points for hit.