How about we just go back to “a promise is a promise”? Or read the Gospel.
What about people who make those promises never intending to keep them; e.g., the person who marries and then commits adultery almost immediately?
Setting aside obvious easy ones like, "suppose you marry a woman and then discover she's your sister".
Are annullments sometimes granted too easily? Sure. Should they not exist at all? I don't think that case can be made either.
What Campion said.