Maybe some enemies wouldn't just rush towards you. Then would try to line up for shot but keep distance. For attacks, maybe some AoE. Maybe some ground hazards. Homing missiles, you would have to bait into enemies.
Good stuff. There was a bug in one build where the stop distance was set to zero instead of varying distances. It was super frustrating having them glued to the player. Instead they stay back some giving opportunities but other than that the rest of the suggestions would be great additions. Not sure it's worth the time anymore though but still useful eventually.