Mechanicals and AI (They've been showing up in the story line,... Now let's put a price tag on them!)
Mechs are there to make your hard life a little easier. Can either add modifiers to successfully accomplish something, or work on its own while you do something else.
They have their tasks already programmed. Just turn them on and let them function.
Variety of uses, such as repair, combat, surveillance. translation, transport, medical uses, etc., etc., etc.
Mechs need repair like everything else. Might require additional university courses for maintenance and repair, usage in combat, usage in medical field,... etc. Things can sometimes go bad, if you forget to turn them off when they are done with their assigned task (Thinking Mickey Mouse in Fantasia here.). More advanced units have been known to sometimes malfunction ("Open the airlock, Hal. Hal? Hal, do you copy?").
Another interesting item that can be found in the wrecks and ruins of civilization and makes it worthwhile risking your safety to find them.