That's the thing. A bad gift is worse than money, but a good gift - something that the couple actually wants and would buy - is better because it (a) shows cons

That's the thing. A bad gift is worse than money, but a good gift - something that the couple actually wants and would buy - is better because it (a) shows consideration and thoughtfulness and (b) saves the couple the time it would take to go out and buy the item. This is the principle behind wedding registries, of course.