Well, call me crazy, but maybe it was because they wanted to extend the capability of an AI over games like chess and go, and while those are still skill intensive, have patterns and sequences that a machine can easily detect and utilize. Perhaps they wanted a more open environment to further develop the tech.
Not only that, it adapted real fast to any cheese that would've worked against it. The players would drop items from their inventory to confuse it, and gain ground against it. Something that was reasonable to assume it would work against something that doesn't really have a way of dealing with really just out-of-the-blue crap. It learned what to do when they did that, and the trick never worked again. That's the worry I have when it comes to playing games, playing an AI that can predict you in but a few seconds of engaging with you, and always being able to see through any mindgames you try to play with it. It shouldn't surprise me how it acted and how fast it adapted, but holy shit does it interest me.
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