Yeah, this completely baffled me when I saw it live. Not only were they not running it, they weren't even faking it: Bradford was in shotgun with 2 receivers on each side, there was an empty set I believe in there as well.
Even if it came down to Spagnuolo's decision, you'd think SOMEBODY within the organization would be saying, "uhh, hey Spags, you think we should run it here?" There's no reason Jackson shouldn't get all 7 touches from the one. I don't care if everyone knows it. Anything a yard or less and it's TWITTY time (that's why I'm tougher than you). Feed your horse and let him finish the job.