Because at that point you are narrating game mechanics not story. I think most DMs who fudge care more about the story than the game mechanics underneath it. If players really wanted to do nothing but narrate mechanics, 4E would have done gangbusters because that system was custom-made for speaking entirely in mechanical terms when having fights (as is evident by so many people who were irritated by so little fluff being attached to powers almost as an afterthought.)
So change my proffered quote to "I'm unhappy with the roll. This is what happens."