Something shifted when the Playstation was released - it was partly the product and what it was now capable of, but partly that a generation of console gamers had got to college/uni age and didn't want to put their controllers down. Everything started getting more young-adult oriented and within a couple of years the image of the gamer had shifted from relatively uncool 8-16 year olds to relatively cool 16-24 year olds.

The more "adult" games had usually been PC affairs before and PC gaming has always required a certain amount of geek to make the most of. Playstation put adult themes into the living room and nobody had to learn to fuck around with their config.sys to get the sound working.