There is a human element to managing people that AI simply cannot do. A boss (good or bad) can change his behavior based on anything from office rumor to the way you look on a certain day. He can decide to go easy on you for a while because he heard through someone else that your dog died last week. He can simply look at you and decide that you look depressed and pull you aside and ask you what's wrong.
Human interaction and relationships are so complex and nuanced that no AI is going to replace it for a long, long time - until we have proper AGI at least.
The only thing I see AI doing is putting some proofreaders and crappy graphic designers out of business.
This is not something that can be fixed by improving the AI, as the true problem lies outside the domain of AI.
Once AI has proven itself to be trustworthy enough, it maybe can perform a mgmt role, but I have no clue how it could ever prove itself without being trusted in the first place.
The supply of even untrained workers is finite, so you have to treat them as people.
We could do this with developers too. Give the biggest raise to the developers with the most lines of code committed, and maybe design a shiny dashboard with it as a number to replace the project manager. What could possibly go wrong?