I have a few complaints, why give a general opinion malus, bureaucracy in this era held just fine, especially for stronger rulers, and usually only broke down due to incompetent rulers, like what happened to the Abbasid Caliphate in the early 800's. It's also excessively punishing when coupled with the centralization general opinion malus of -30, which gives a flat -100 to all vassals total and means you will never have a happy vassal unless you are abusing Viceroyalities and playing 'assassinate the old king-viceroyality so I can give his successor a +70 opinion modifier for doing basically nothing'. You would very much want the centralization as well, as the vassal max levy and vassal tax maluses mean the only way to effectively gain anything from a large realm is to have a large crownlands. This also pairs well with the Statist Soul law chain that gives a whopping -60 vassal opinion in exchange for counteracting the other maluses of a large realm. In addition, -70% land morale is hugely punishing since it affects Retinue, who are the most likely to be what you are reliant on late-game when the modifier goes into full swing, which is why having halved troop maximums and losing nearly 75% of taxes is incredibly crippling as well, I would think a huge realm would flip the focus around, focus on extracting wealth from the territories they control in order to support a professional army.
Edit: I also forgot about how horrid this would be for Anarchic realms, since they are hugely reliant on being able to call their anarchic vassals into their wars, which the general opinion malus would cripple