Kevin Slavin gave an excellent talk [1] on the need for trading systems to be built with humans in mind rather than just for beating the other bots. I highly recommend it, it's certainly one of my favorite talks.
And I, for one, am confident that Wall Street will accept the limits of their intelligence and introduce software constraints that require human oversight for the benefit of market stability. /s
Seriously though, any system with many actors is going to see unanticipated failures resulting from runaway interactions. There is no way around it. And I think that if the threat of losing money isn't a powerful enough incentive to stop it, then nothing is.