How is it a waste of resources? look what wonders it did for the sales of PS4. People were happy to get an upgrade with all the DLC and a few extra maps, even people who owned some of the games repurchased them.
Because if the games were on the market place, it would do the same "wonders" without having to spend time, money, and man power. Time, money, and manpower that would be better used working on new games.