What do you mean by AI hands? You mean by creating an AI?
I mean, it's not as impossible or hard as people make it. Granted, I have A LOT of experience eventing so it's easier to me then it is for others, but when I was learning, it's not as hard as people make it. I'm talking about all you said about AI, rolls (which I assume is dice???), or scoring (which I assume is keeping score).
I will also add it's partially because scripters would have to accommodate for a lot of customization options which eventing, when set up, can do a lot easier and faster and it'll be to the liking of the eventer. <= this sentence I heard from another scripter. First part is just my opinion on eventing.