I have to agree with that. Taking on an "unequal marriage" should have just those consequences. So marrying your unlanded steward's daughter because you got her pregnant should get you piety points, but draw the ire of your peers and the members of your dynasty.
As to AI approval, I also agree. It should be about comparing status and landholding; it should also be possible for both the AI and player to defy their liege's or parents' decision against the marriage, with suitably bad consequences.
and consequences are what makes games fun