Here's the thing...
"Most" consumers buy games at Gamestop or similar retailers. These retailers DO NOT place large orders for games that aren't Call of Duty, Madden, or as compared to sales-wise in this case, Zelda. These 3 games will definitely sell, so the store will order at least 70 copies each.
Shadows of the Damned, is just another "random unknown game" or low-seller, to the people in charge of purchasing inventory. So when the store only receives 6 copies total, that's all it will sell. When those copies are gone, that's it. No reorders, because, well, there were only 6 sales of this game.
If a retail store doesn't order enough because they base sales solely on pre-orders instead of stocking that front shelve right behind the counter with ALL of the new releases that day, then the game's sales are doomed.
Tl;dr version
I blame the retailers for not stocking enough of unknown games, as opposed to gamers outright passing over the game for something else.