I don't find your comparison all that well thought out because the Last of Us isn't a RPG from Japan. It's a Survivor Horror game and games of the genre always had more mature themes and grown up characters even in the nineties. Games like Resident Evil, Silent Hill, Dino Crisis, etc. Japan just always tend to use much younger characters when it came to a lot of their RPGs with the exception of FFVII (most of them being at least in their early twenties) and I forget how old the cast of Legend of Dragoon were.

Yeah, games have evolved and will continue to evolve but they've been maturing a lot longer than you think. GTA goes back as far as the PS2 and it had you banging hookers, God of War turned sex into a mini-game, in the first SmackDown vs. RAW game you could hook up with Torrie Wilson in the shower and it would show her bra being thrown over the showers door and onto the floor. Command and Conquer originally came out in 1995 and it shows a guy being shot point blank in the head. Mortal Kombat was bringing us blood and guts since 1992.