I can see the logic in abiding by the rules. SK won't make any money now by not allowing you to change flights, but perhaps next time you buy a ticket you'll be inclined to buy a more flexible one? Or realise that you have to pay the change + fare upgrade fee to change.

That said, I would love it if we were able to stand-by on earlier flights like many airlines in USA allow. That way SK could utilise non-sold seats and overbook flights more.