Interesting idea. Final Fantasy 12 is my favorite game that allows you to "script" your characters' moves, but you're only ever fighting against the computer. Incorporating this into a programmable MMO seems like it could be very fun, and somewhat parallel to the way stock markets work with everyone using algorithms to compete against each other.
I really enjoyed the Gambit system. It felt a lot, at times, like playing with other people in that you'd have those "noooooo, don't do that!" moments (despite them being unanticipated use cases, effectively). You'd also have your "other players" get more sophisticated over time as you acquired more fine-grained Gambits in parallel with you getting better at the game.
I definitely think this concept would have legs. Even for an MMO where you could make a rudimentary party and go do something if the rest of your play group were asleep during the middle of the day.
