It's turning a game into a skinner box designed to extract as much money as possible from those who buy the game. It operates on the same basic principles as slot machines.
The counter-argument goes that people "should know" and be responsible with their money, but I'm not a fan of that argument. It relies on people being perfectly rational actors that they just aren't.
I'm personally in favor of instituting regulation for these things. Even if it is just purely from the "we have to protect the children" angle - children are arguably the main market for these strategies after all.