I don't think the Galaxian example is actually an example of A.I. The game code more than likely states to create a group of enemies and move them in a bombing run group, rather than multiple enemies that were randomly spawned deciding that they stand a better chance of killing the player if they group together and perform a bombing run attack.
I've never programmed A.I. before, and as such I don't know how many of these suggestions are implementable to the DB programmer, but having thought about it, I've come to the following conclusions about your A.I. 'ethics' problem. Good A.I. progression of difficulty can encompass many features of the enemy playing-style, ranging from totally decision-dependent to options on the outside of actual decision-making:
Increase in number of possible options...
Such as different types of enemies being equipped with different capabilities. Not really an A.I. example but it ties in well with a later point.
Quicker decision-making...
The dumber NPCs will have a longer delaying mechanism in their decision-making code, the length of which will decrease as the difficulty of the NPC increases. E.g. in a war game, the regular infantry will take longer to make a decision because of their lesser degree of training, whereas the Special Forces infantry will have excellently short decision-making times.
Larger span of awareness...
The range in which the NPC will respond to the player, for example the range of hearing or sight that the NPC has. Again, this isn't really an aspect of A.I., but it is important when used in conjunction with the other aspects.
Probability of choosing the most effective option...
The NPC has to make a decision from a multitude of different options. Different levels of NPC intelligence will precipitate differing tendencies to choose the most effective or lesser effective responses. E.g. a soldier trying to find someone on his own is more likely to get killed... he did not choose the most effective option. The more intelligent soldier would get his colleagues to help him search for someone, or would sound an alarm.
Any insufficiently advanced magic is indistinguishable from technology.
Druadan - Avalanche Interactive