This is the real X-com, not the simplistic new version. If you turn it into a console-like game for kids who don't want to use their brains while playing, then maybe you have a point.
The mechanics is already in. You just need to use your brain. Front armor is already heavier than side or rear armor. IF and ONLY IF you are behind cover, the game mechanics dictates that flanking (depending on how much you flanked the enemy) increases your chance to hit. Why you would make a rule about extra damage and is beyond me.
