I think when it serves you.
Ambigious I know lol, but speaking from experience my anger has helped me a lot when it comes to tripping and psychedelics, specifically when dealing with pre-flight anxiety. I have this inner rage that comes out from time to time (I use rage for sake of emphasis, it's like a very strong focused, willful emotion). Since I'm naturally a person who deals with fits of anxiety, trying to work myself up to take a psychedelic can be... difficult. My anger has served me many, many times by calling me out on my irrationality regarding my apprehension. It says to me 'what's the problem' and I say 'I'm afraid', to which my angry side responds with 'well then don't take it you big baby! Give up on your little psychedelic research project and become a just another brick in the wall like everyone else if your so afraid'. I can never accept this alternative, so I pretty much dive in after that.
Honestly, without my ability to get angry at myself (when I'm irrational) I'd be very complacent in all aspects of my life. So in that respect, anger does have it's uses but only when properly focused on stuff that you SHOULD be angry about!