Call me ignorant (you wont be the first or last) but you keep refering to player agency (you mentioned it in another thread).I just want to know what your definition of it is. I'm not trying to pick a fight, I seriously find myself in the dark on this. Is it players taking more of an active role in the game other than simply rolling dice when the DM says so? That's the only thing I can think of.
On the subject at hand, I do try to explain to my players why I feel I should trump the rules either in their favor or not.
How players make decisions, what their choices can affect within the context of the game. For instance, in a railroad, player agency is constrained to decisions that can be made while remaining on the tracks. 3e allows for great player agency in creating and shaping characters -- so much so that it becomes the game for some. DCC RPG enhances player agency in terms of making decisions from the context of the game milieu (from the point of view of the character), while 4e restricts player agency very much to its rules structures (so much so that it is difficult to know what is happening from the point of view of the characters in some circumstances).
(Deciding that X happens regardless of what the players choose or do also undermines player agency, as it makes the value of their choices illusory....as when a GM decides that X lies either right or left, regardless of which path the PCs take.)
There is also GM agency. For instance, WotC-D&D has long combat times that cause a disproportionate amount of the average session to be spent within specific combats, which limits GM agency in terms of presenting minor encounters, especially as levels increase. DCC RPG vastly increases GM agency in terms of presentation, scenario creation, and world design.
Hope that helps.....?