The start was a stick of dynamite, trouble was the writer lit the dynamite and then the fuse burnt from there and ended on a ladyfinger bang. A beginning that burns bright tends to fizzle. The writer spent 6 months or more on that screenplay and couldn't find an ending that was both emotionally and intellectually satisfying. That spells trouble, and it is common with HC in any format. Next time they came to me with an idea, the first words out of my mouth were "great! How's it end?" I got the blank stare, and said come back when you know, LOL. Novels have the advantage of being unlimited in length and scope, but it can also lead to trilogies (or god forbid) a giant series without a real ending. Pantsers with big ideas will often get muddled down in this situation, and it can last years in novel writing... been there done that.
Tomorrowland is a good, recent HC example that didn't totally fail, but demonstrates the lack of satisfying ending on both an intellectual and emotional level. 50/50 movie on rotten tomatoes with a 90+ HC that failed to retain its momentum, and finished with an "that'll have to suffice" ending.
My personal thinking is HC is great, but if you're rummaging for ideas, look for High Concept endings, and work backwards, rather than the all too common High Concept beginning that struggles to launch.
From what I gather of your criticisms, you are against the idea of basing an entire story around the "geewhiz" factor. Writers who begin their projects believing that the mere inclusion of a geewhiz idea, some bit of "awesome," will be enough to carry a story will end up fizzling somewhere midway in the writing process and have bad endings.
Pitches for high concept stories pitch that geewhiz factor. Because it's the awesome. But "geewhiz factor" does not mean "great story."
I will not argue with that. Any number of examples can be found. Once the geewhiz factor is introduced, in the first 20 pages or so, what's left to sustain the story?
Sanderson's suggestion does not seem to me to be "Create a high concept story." Rather, it's a suggestion to brainstorm ideas that will help you take a bland, generic world and make it interesting. Perhaps this also applies to bland, generic characters, since he also suggested taking some element of a character and pushing further.
There is a wide gulf between a) "Have one weird but awesome idea and make the story about it" and b) "Use a weird but awesome idea to give your world its own personality."