It's almost certainly wrong to think of WWII air attack as being more accurate than artillery fire, even naval artillery fire. The art of coordinating between air support and the front lines was in it's infancy, while Artillery had many years to work out detailed plans for how to support troops, even outside visual range. Naval artillery was perhaps less practiced at coordinating with troops than field artillery, but the principles of how to manage it were well understood. Coordinating with troops is essential for accuracy and effectiveness because it's the front line troops who have a clear idea where exactly the enemy front line defenses are.

There is also a mechanical advantage for artillery in that it can adjust fire based on previous misses. Forward observers can radio back to ships and correct their previous misses. Whereas a WWII aircraft will have difficulty coordinating with ground troops and will only have the one bomb run so they have to hit the first time.

Naval artillery also has the advantage of being a "toolbox" so to speak with Battleships and Cruisers being able to deliver large caliber shells from far away, and destroyers or even landing craft being able to deliver smaller caliber shells from very close inshore. If a destroyer or landing craft can fire "directly", meaning they can see their target rather than shooting by radio at designated coordinates, they can be very precise indeed and smother the target in fire.

Finally, artillery is good at STOPPING when they are supposed to. The WWII doctrine (and WWI) was for artillery to suppress defenses and then infantry assaults them immediately after the bombardment is over. WWII air support was not nearly as good at making sure they stopped once the infantry moved in. Aircraft frequently mistakenly bombed their own troops, disorganizing the very attacks they were intended to support.