First: I just have to say the poll is set up on the wrong premises, and is therefore a stupid poll.
Second: Some misconceptions about the terminology here in this thread.
Ballista = stone projector / gr: Lithobolos
Catapulta = arrow projector / gr: Katapeltikon
Ok.. That out the way, yes I really would like this in the game, because it is realistic and historic. But it would be limited to only a few Greek city states like Syracuse.
Yes, there is plenty of historical data for this. One example that springs to my mind is the fortress of Euryalos connected to the New Wall of Syracuse, on the west side of the Epipolai Plateau. This is after all where the catapult was invented. The katapeltikon (arrow projector) and lithobolos (stone projector). Later the Romans called them Catapulta and Ballista respectively. The fortress of Euryalos was built solely for the purpose of having stone projectors and arrow projectors on top of. This held the North of Syracuse safe until 212 BCE when Marcellus invaded it.
Other than Euryalos, there's been many more finds in Greek territories of walled artillery positions. Schramm excavated and analyzed the ruins at Ephyra finding the same. Washer-plates from catapults were found, and the walls were of sufficient width and volume that they were not just meant for soldiers.
No they weren't. But they learned quickly in their confrontations with the greek successor states. It was the Assyrians who invented siege warfare with the battering ram in the 9th century BCE But by the time of Rome 2, the Greeks were preeminent and without peer in the realm of siege warfare. The Romans weren't even close. The Sassanids did not have artillery in the sense of the Greek school of thought. I'm not saying they never got artillery, I'm just saying they didn't start out with it, but learned from the Greeks. Same with the Romans.