But it clearly was broken, as it was a major source of AI stomping combat-wise (since the AI couldn't use it effectively).
G
I'm not seeing this AI stomping, and certainly not due to flanking. Watching the diety players, it seems far more a combination of melee shields with strong ranged and artillery attacks that let them "stomp the AI". Heck in that situation flanking is helping the AI because there the ones often attacking in melee, while the human units sit there and soak damage, allowing the ranged units to do work.
But even if it is somewhat responsible, I will drop back to my other argument. At the end of the day, you can't remove human vs AI skill gap. As long as the combat is tactical, the human will be better at it. You have to pick your battles, and I think this is a losing one. You have upended a number of systems that now have to retuned and re-balanced (aka another 3 months before getting to gold), and taken away a fun tactical puzzle for the human (because a 5% bonus is not worth the trouble).
All for something that honestly doesn't seem all that abusive.