Directors being sociopathic dicks aside, the fact that you *can* get reactions is entirely outside my point. Those actors could certainly have given those performances without those stimuli. What you're describing is called "The Method", except because these directors are stupid sociopaths, they don't trust their actors to use the method in the appropriate way. See, the normal way that shit works is that you find a piece of yourself that maps to the moment in question, and then you work on that mapping internally until it fucking clicks. You don't use shit off the cuff, and you don't fuck around with things you're not ready to use. Putting the stimulus into the real world eclipses any hope of actually doing that work.
I've cried in productions. Cried to break my worthless little heart. It's not fucking hard. It's hard not to when you get the work done and you get into the scene. There's nothing interesting about taking the option of doing the work out of the actor's hand; it's quite simply something that caters entirely to someone's worthless ideas about what they want.
You can't have everything... where would you put it? -- Steven Wright