over zealous blood crazed armywanting to shoot the closest thing to them to eradicate everything? sounds reasonable. But I wouldnt enforce it.
It isn't a question of not enforcing it. It is a specific rule for the BT. It is characterful and fluffy like you said. And in about 80 games I have failed the roll about... never. I rarely shoot at anything other than the closest models, use a lot of vehicles, and focus on CC units not shooters. Lacking devastator squads removes the problem to a great degree.
Finlay: Have you REALLY read the Black Templar text? They are the most zealous SM chapter that exists. They have never stopped the Emperor's crusade in the 10,000 years since his installation into the golden throne. HE never said to stop, so they assume everyone else is a bunch of duty shirkers. They do not set up fiefdoms like the Ultramarines and Space Wolves and think that to do so is a direct violation of the purpose of the Marines. Space marines are meant to protect all of humanity, not just one section at a time. This is also why they ignore the 1000 marine limit. The Space Wolves do too, but the Black Templar are the most numerous. Only their EXTREME piety prevents them from being examined by the Inquisition. The only time they were they destroyed the inquisitor and the the issue was swept under the rug. There are at least 5000 templar and probably around 7000. Many people continue to be suspicious since almost 1000 BT were seen at Armagedon, which seems... unusual. They were known to be active in several other crusades at that moment. But the High Lords were okay with it since a BT has never fallen to chaos and they go wherever they are asked without delay or complaint.
In other words, they are completely and totally awesome in everyway a Space Marine should be. They aren't Twilight marines or super moody like DA. They are born to kill and love every second of it yet are not complete nutters like Chaos marines or orks.