I think a lot of people seem to assume that operator animation and transport affect the micromanagement, readability, and cadence of siege weapons. Truth doesn’t interfere at all, if you look at the US gatling guns they have scary agility and rate of fire, and they do have siege operators.
If there is artillery in AOE-3 that is slow, it has nothing to do with the operators or the horse that pulls the cannon, it is due to the design of the unit. For example, AOE-2’s and AOE-4’s stone throwers take a long time to assemble, and also move slowly. The same goes for AOE-3 mortars, they take a while to position, are slow and have a low cadence of fire. It has nothing to do with the operators.