I think the industry has changed. During the PS2 era, gamers were more hard core. During the 360 era, gamers became both casual (for a time) and dominated by the dreaded dudebro. I think right now, the demographics have shifted back in favor of the people like us. I mean, you have COD, sure. But look at the games that are getting the most hype. Bloodbourne? Would a game like that have mattered during 2006? Probably not.
The leading system dictates the trend.
The PS1/PS2 were dominant Japanese games eras, mostly mature games, that were dominated by an rather dev friendly japanese company and its systems.
360 lead the 7th gen hardcore gaming by being the dev friendly system and being an North American company it's game style shifted to it, more war, modern thematic games.
Even though the PS3 catched up and the Wii also performed better, the year lead and hardcore US dominance dictated it almost the whole gen.
Now it came back to the PS4, games are going back to being more about mature phantasy, it also remains with the roots from the past gen, but it's showing it's influence.
The same before that as well, Nintendo times being the major system dictated the more soft phantasy thematic that's their focus.
It becomes pretty clear when you look at it this way:
3rd/4th gen: Nintendo influence. Platform domination. Less focus on story and mature themes. Phantasy.
5th/6th gen: Sony influence. Nintendo roots still on 5th gen due transition. RPGs become very relevant. Expansion on genres popularity. Story driven games/ more mature phantasy. Platforms still relevant on 5th gen due Nintendo roots.
7th gen: Microsoft influence. Sony roots still there due to transition/take back. Shooters become huge with American popularity on exploring modern/future war thematics. Genres retracting to focus around this modern influence. Online model expansion and becoming highly relevant, pushed by Live firstly. J RPGs downfall.
8th gen: Sony influence. Microsoft roots still there due to transition. Modern war thematic still relevant because of it. Genres re-expansion. Easily adaptation to mature phantasy comeback. Japanese developers getting way better envyronment to try again.
That's basically the leading/influence company traits being reflected on the envyronment.
Sony influence is expansive as not focused on single/few genres, better for Japanese developers and still attractive for Western too.
Sony model drives success more easily, it's better for the envyronment IMO. All kinds of games going on, better for the big scope.
Jap devs have less power (money) now, so they also could use this better enryronment for them and are doing so.