And you know what, it works ? why, because it was scripted by PEOPLE. People with real intelligence... people do the work so the 'AI' doesn't have to, and it does a much much better job. And it should.
It's not entirely scripted though..
Im not sure what your on about, but i'm pretty sure when one enemy meets its own enemy it tries to kill them... what kind of a statement is that 'programed to kill', what do you want them to do have a big bubble party and then ambush us ?