I know monks have this sort of thing disabled for a reason until whatever is done to them is done.
But for everyone else, and even for and especially because of "pugilists" who are not monks who have all monk bonuses - let people who are using parry to get the offhand free AC, get it, so that they can look aesthetic and cool. It also means people can spend 30 points to not have to use meta shields and instead have a torch or lantern or whatever.
There are plenty of shields that have amazing bonuses and way more ac.