While it may no simulate reality well, the setup currently gives an overall balance to the three main melee fighting styles (sword and shield, two weapon, two handed). Once you start fiddling with that, you start to move player choices towards one of those options. In a game without feats, these three are used in roughly equal numbers (IME), but with feats two handed is way more common due to GWM and PAM. Adding additional modifiers to two handed weapons is going to push almost every non-finesse melee build into using it.