I think the industry is trying, but is somewhat stifled by producers who think that gamers need something actiony, and can't play a whole game without being pandered to. Couple of examples: *SLIGHT SPOILERS AHEAD*
Heavy Rain: A brutal game, that did not beat around the bush, punches you in the face with messages and subtext. Mature? To a certain extent, but they throw a dream sequence with the lead female protaganist in her underwear fighting off robbers.
Reason? The only thing i could think of why this happened, was the game was more relaxed until then, and they needed something to capture the audiences limited attention, rather than think we could handle something that breaks the mold. Action and story really kicks into gear not long after then anyway, so the whole sequence is nonsense.
L.A Noire: A game that tried something new, interrogating people, a no nonsense, adult look at nudity and death. Showed the protaganist as flawed, and doesn't give him many relatable qualities. Then over the course of the game, the audience slowly starts accepting him, and relating to him. No mean feat, honestly. The audience had been playing a mature game, under the hood of the most traditionally immature genre there is, the sandbox. And gamers accepted it, and played it through.
Until the end, where all pretence of trying to be mature and different end. The end of the game, rather than folow with everything that made the game, they decided to just give the player a flamethrower. And turn it into a corridor shooter. No conversations, no learning motivations, no nothing. Go in a tunnel with a flamethrower and torch people. Why this sudden shift in genres and tone, and why, for all that is good and holy, give the lead a flamethrower? I think they run out of ideas to have the gameplay be the same, conversations, arrests, etc. and still have the greek tradgedy ending. The reason this ending is immature, is not because it is poorly designed, or heavy handed, or even the genre shift, but because the game falls back on something it knows gamers will push on with, despite playing 20+ hours on the game beforehand. Rather than back itself, it turned itself into what 15 year olds would like, despite them same players would have turned the game off hours ago. I believe the studio still thought, after succeeding at making a mature game for the last 20 or so hours, that it was still a game for gamers, and that gamers are 15.
This is a confusing and pervasive trend, that still sticks with the industry, that somehow, all the kids who played SNES, or the Playstation, gave up when they hit puberty, like they would action figures or barbies. The average age for a gamer, i think, is 37. Yet the industry still thinks it is 15. People don't just "give up" on gaming. Oh, some do, but not you know what i mean. I believe most developers are slowly coming to terms with their market audience, but the publishers, the hives of scum and villainy, force them to make the games like every other game, in order to maximise profits.
So, rather than the games themselves becoming more mature, even though they slightly are, i belive the perception of games maturing, comes through eyes that themselves are maturing. We as players slowly percieve the world differently, so look deeper into games than we might once have. This is the same with movies and books. The game industry needs to catch up with the perceptions and maturity of gamers before they can become mature.
Jesus that was a long one.