It is, actually, historically correct. Hence I personally don't think it's a bug. Even though I'm sure Taleworlds didn't do that intentionally.
For example, I think this can be also counted as a bug:
- When you charge your troops to an enemy, after a few seconds of a clash, some of them (a sometimes big portion of your army ) chases the already running away soldiers, even though the battle is far from being over and a few meters away there are lots of enemies still waiting for them to attack. This breaks your formation and makes you more exposed to remaining soldiers.
But this, also cannot be classified as bug because it is something happened quite often in history. So frequently that some historians say that Athenians won the Battle of Marathon because rookies/recruits -surprisingly- didn't chase the running away soldiers and kept their formation. And pushed back the enemy as a single block of force. But I'm pretty sure Taleworlds didn't consider this human-behavioural case specially.