Waylander the Slayer said:
Does anyone have any instances of when good writers/story tellers sucked at Gming?
Hm, I've never had a writer DM. I know people who have though, some have been happy with it, while others have experienced the most stifling railroading 'in the interest of the story arc'.
Speaking as a DM who also writes:
Dunno whether I'm any good as a storyteller or writer, that's for others to say.

All I know is that when I write a scene or story, I often get better results when I let the characters have free rein for a bit than when I press them into my plot.
(I agree with you that King's On Writing is a very useful book btw, although it still doesn't make me want his actual stories.)
But I also know that in the final analysis I'm the one who decides where the plot goes. I decide on which cool scenes to include or to throw out, I decide which of all my possible endings I'll be using, heck, I decide what character's POV to tell the story from!
When I run a game, I think differently. The story isn't for me to tell, it's for all of us to create together.
I guess I do use similar techniques for presenting a location or encounter as in writing, for fleshing out NPCs and giving them quirks and motivations of their own insofar as their potential for the game warrants that, and although I tend to run fairly combat-heavy games I get dissatisfied and bored unless the combats I run make sense to me, at least behind the scenes.
But Whether my players ever find out about any meaning I give things is another matter. Sometimes PCs investigate in-game, sometimes players ask me to find answers. If not, I live with it. I'm not 'telling' a story, I'm presenting an environment for my players and me to create one together.
I also don't aim at forging a plot arc (through planning, guiding play or whatever) that would hold up to scrutiny as dramatic development in the sense of a story. I hate playing under DMs who do that (and I've encountered them, although the ones I've experienced weren't even good at telling a story) - so I try to not do it to my players either.
