Worth Fighting For
why flanking house rule
Flanking gives bonuses to both attackers because the defender is dividing his attention between them. If an opponent doesn’t pose any real danger, you don’t have to divide your attention from the one who does. Lycanthropes facing foes that aren’t armed with silver weapons, as well as characters with very high Armor Classes facing much weaker foes, don’t need to worry about being surrounded.
You can use the rule to limit sneak attacks against you because rogues can only use sneak attack when you are flanked (dividing your attention). If you focus entirely on the rogue, he can’t sneak attack. The danger of course is that the other attackers get free attacks on you (attacks of opportunity) and you don’t get your Dex bonus to AC against them, but if they pose no danger to you (as in the Lycanthrope example above) that’s not a problem.