I was comparing the prices on the same day (default prices), not 1.5 years apart.
Don't be obtuse, they were introduced 1.5 years apart, you know damned well what that means, and no one buys the older SKU because, duh, there's a GOTY edition. However it remains up for sale because it costs basically nothing to keep it up for sale.
You're comparing the price of a release day game/expac/dlc to the price of the longtail GOTY one, it's apples and oranges. Your GOTY version didn't exist when the first one was put up for sale. Your argument is basically an argument against ever buying anything within the first 4-5 years until it's hit its absolute bottom price, because otherwise "it makes no sense, it'll be cheaper later!" That's not an argument against DLC, it's an argument for paying the least possible price for everything.