Hi Barron,
that's a good question, and that was my first reaction when jostapo suggested we do UA.
I can say that I didn't fully realize the difference between the two until I started setting up test missions with UA.
As you know, I also did a pretty involved camcreated artillery suite.
So let's leave out everything else, and ask:
what advantage does the UA ballistic system have over making the artillery fire fake shells and camcreating shells over the target? Why bother with all these fancy 2-minute TTL hacks and neural nets? How can you tell the difference?
Well, I see five major advantages.
A) Sound. In spite of what might be thought, you can't "fake" dynamic 3D sound. You get all kinds of sounds: Shells passing overhead on their way to a target 1km away, the different sounds of High- and Low-angle fire. With the doppler and some experience, you can tell if a round is going to go long, short or hit you. And that sensation 3 seconds before impact of "I'm going to eat this one" is priceless.
B) Trajectory. Believe it or not, RL artillery shells don't fall straight down. Artillery works very differently on slopes or in object-rich environments like towns. Try hitting a hilltop with low-angle howitzer fire in UA, or take shelter behind a big building during a barrage. Yes, you could just spawn shells and setvelocity them in the general direction, but at that point, you lose the advantage of precision.
C) AI interaction. When a unit is killed by a UA HE round, the firing unit gets credit for the kill. EVen better, the AI becomes aware of the firing unit. That means that an incoming round triggers AI "under attack" actions, which doesn't really occur with created shells. Also, if the AI's on guard, and the unit's close, they'll even go and take out the offending artillery.
D) Added depth. Most people are just going to use UA and shoot with it, but for those who want to become experts, UA can be rewarding. For example, the dynamic nature of UA means that the pattern of shell hits varies across ranges. Thus a skilled observer will take into consideration range, terrain and target type in setting up a fire mission. And someone could "read" the sheaf and guess where the enemy shell is.
E) Realism. Anytime you fake something (And we all have that need from time to time), you limit the "suspension of disbelief" element. Yes, it's true I'm biased: I've made missions with both sorts of artillery, and I know darn well what the differences are.