There are genres of video games much more deserving of strict regulation than "brain-training" games which may or may not be backed by science.

Way too many mobile games I've played function like casinos. Their goal is to make players spend as much money as possible and the game design reinforces such behavior and also keeps the player coming back like an addict attempting to avoid the negative symptoms of withdrawal.

When it comes to the safety of players, I think these money sinks are a much bigger concern than games that may or may not enhance cognitive abilities.