I’ve noticed it too, but its fairly easy to get around it. For example, I always remove my repulsor before I do campaign farming - its not necessary and the AI just uses it to prolong battles. So, in your example, remove your grim raptor and/or any other crap weapons when you farm.
And, of course, choose missions you can easily beat. Because AI will never be as smart as you… until Terminator that is.