I see very little point in such an option

Really! the reason why this was important to a lot of us was because we can calculate the fall of shot a lot better than the AI. For example when targetting moving targets one has to aim at that point where one assumes the target is going to be, something the AI failed to do at least in the earlier titles.

With this option available we no longer have to target units and wait for the AI to do its calculations, instead we can now adjust aim manually using the attack ground option. Additionally as we now have unlimited ammo for arty there is no limit to the time that we need to do so.

artillery at the time fired so slow and so innaccurately

I was refering to that which is available to us ingame which doesnot necessarily conform to reality.

Also bare in mind that most artillery peices can't fire in a high enough arc and might just end up putting cannon balls through the back of your forces.

Mortars, Rocketlaunchers, Howitzers need I say more??

In the demo the American artilery acted quite sniper-like. I couldn't move my battery anywhere in US arty range without getting blasted into pieces - several times while still on the move, usually without even getting the opportunity to un-limber. This was somewhat puzzling, IMHO

You were attempting to get into an artillery duel with horse drawn 6-pounders against 24-pounders, what do you expect??