The point is simple: to collect their 'conquest'/'romance' cards.
It's funny you should mention that because I thought about that, but that's kind of an example of what I mean by saying it's pointless.
Where are these conquest/romance cards? There's no way to look at them afterwards is there? Is there somewhere in the game you can see how many you have collected? They are not an achievement or anything like that, are they? I'm just saying that if you are going to have something like that in a game, let there be some kind of reason you would want to discover it, like you meet her again later and she helps you, or maybe she's married, and her comes after you. How about you gain a talent for discovering a secret? A comical animation? Something, anything.