To be honest, the judgment of the frontline officers was not flawed. Anyone with a bit of tactical knowledge standing in Charlemagne's shoes would have done the same. It's a clumsy, crude, and ruthlessly cold tactic, but history has already proven its effectiveness and its tenacious vitality throughout the annals of war. Even with the progression of the times and advancements in technology, it can't be eliminated—just replaced with endless streams of thousands of armored vehicles, or swathes of strategic bombers.
But so what?