amok: There is no point at all. It is a collectible thing, and like most collections of anything there is no other point than in the collection itself. Some of the cards are quite nice, though, and some developers use them to showcase concept art and such. Some I would like to draw attention to is the cards for Tower of Gun, where the developer explains the reason by each, and the art work for Defense Grid - pop art at its best. So apart from this, yes - there is no point.
Yup, they're a nice collectible. Some are pretty. No real point, but I get a nice, fuzzy feeling similar to the one I feel when I buy dirt cheap a GOG game that I just know will never get to the "actual play surface" of my backlog. Or with all those bonus, soundtracks and avatars that I probably will never even download, but still want to get with my GOG games ^^