The issue of fudging vs fate is as old as D&D itself, and outside of Gygax's notion that all rolls be fair regardless of outcome, most of the advice I've ever seen in RPGs is that in a choice between fun and fair, fun should win. So much so that I thought it was universally assumed a DM can alter his rolls in pursuit of the greater good of people having fun. (The notion that a DM who does is cheating wasn't something I ever saw expressed until within the last decade, when OS purity became en vogue).
Which I think is why I prefer separate game systems rather than merely DM advice when it comes to game systems. 2nd edition (where I cut my teeth) was a terrible mismatch of expectations and rules. 2e wanted narrative focused adventures with heavy role playing and storytelling and then used a version of D&D that was full of instant death, randomized chargen and shackles on PC power. No matter how many essays the Dragon Mag and the DMG made, the rules were at odds with the mission statement.
So if a game comes along with a "let the dice fall where they may" style of play (something like Hackmaster or DCCRPG) the rules will support that, and a game like Doctor Who AiS&T which is all about the narrative over the dice, the rules support that. But I wouldn't want both to run off the same engine because their goals are too widely different.
I think this cuts to the heart of it. If I as a DM have to fudge the dice to make the game work, something broke. I either overdid things on the encounter scaling side or the game was way too swingy, but what I don’t want to see is something in the rules that undercuts that and says “If you didn’t like the outcome, just fudge the result so it’s what your table would prefer or what benefits the story.”
No. That’s what I’m looking to you, the designers, to help manage. If that’s simply the rules and the way the game goes, I want the text to reflect that. I know I can always fudge the roll. You, however, shouldn’t get the easy out as game designer to make that acceptable.