It looks like everyone is saying the same thing here, which I agree with, these games just have inherent problems with core game mechanics: those things that are expected out of a modern video game. I really enjoyed reading the article on Mirror's Edge, because much like Mr. Cook, I also spent my summer playing Mirror's Edge, and it was one of the few games I thoroughly enjoyed playing through on each difficulty and trying to master the time trials was an intense and exciting challenge. So, it also frustrated me to have to come to the fact that this game which I had spent a large chunk of the summer playing and enjoying was, in reality, a bad game.
My friend also has this same problem only with a different game that came out recently. He always reminds me how frustrated he is with the reception on one of his favorite games: Bionic Commando. I've never played the game, and I probably never will. But that doesn't stop him from discussing ALL of the reasons that he enjoyed the game. And then he'll stop to tell me that there WERE, of course, inherent flaws in some of the mechanics of the game and the story (those core parts that make up all video games). But there is still nothing that will stop him from loving the game that brought him so many happy memories.
So, when you talk about the things that bring a game from being amazing to only being 'meh'; those innovative titles that just didn't have enough 'Chutzpah' to make them a Katamari Damacy but also didn't have enough investment to make the game into a Call of Duty. It really comes down to those core game mechanics, the ones that these developers have been wrestling with since QBert: Story, Game development, and Themes. These border-line games have them, but they fall JUST short of expectations.
Also, you ALWAYS need more Cowbell. Thanks, Russ, I love reading your Editor's Notes.