The question of the causal gamer versus the more serious one is one which is, to me, an artificial one as it's entirely possible to play Jade Empire on your phone now. Angry Birds is no more a causal game than Super Mario Brothers was at the beginning. No, it doesn't possess the epic storyline of the original Fallout or Baldur's Gate but it is representative that demographics are changing.
But, IMHO, not fast enough.
I'll get back to that.
One of the more interesting cases to address is how the Final Fantasy series morphed when the developers discovered the majority of the players were becoming less and less males and more and more women. By Final Fantasy VII, they started developing the series with the idea they would be marketing toward women every bit as much as men and now the latest edition of the game was designed with female gamers primarily in mind.
When I bring up issues of diversity in gaming, my primary concern isn't that it should serve some artificial quoa but it's my belief that games will simply benefit from mixing it up a little. Take for instance those venerable institute of Mario and Zelda. In the 1980s, Princess Zelda had a action hero period as part of a cartoon.
There was also SMB2 which had Princess Peach as a playable character option. When I ask for the option to play them, it's primarily simply because I think it would be fun and I don't see any reason why said games should not exist. One of my favorite characters in the Resident Evil franchise was Claire Redfield and I really enjoyed playing her in RE2 and RE: Code Veronica. I didn't see a reason why the character's gender was a big deal but she was fun to play.
There's been literally thousands of video games which have the premise of "someone has kidnapped your girlfriend, go rescue her." This isn't even a bad thing but falls into the issue of gaming which is the fact the biggest problem in video games with diversity and sexism isn't that game developers are racist but they're LAZY.
The Assassins Creed franchise has had two female protagonists in the entirety of its career with Aveline regulated to a side console and Evie, a significantly more interesting protagonist than her brother, taking forever to get some decent screen time. The games are paralyzed at the prospect of mixing it up with Assassins Creed V being the horrible sucking tumor it was because of the attempt to redo Assassins Creed II, Brotherhood, and Revelations over again with its Ezio-rip off protagonist and a swashbuckling conspircay story which is the absolute worst thing you could for the french revolution.
Why was Arno a better candidate than Elise, Aveline, Adewale, or even Connor? Beause the game industry wanted another Ezio and didn't want to take risks.
Customizable characterization has certainly opened things up but New Vegas summarizes what I want more from the gaming industry and it seems determined to be less. Fallout 4 has a female protagonist option but it was clearly made as a slapdash add-on since the beginning of the game opens with the MALE protagonist talking about HIS grandfather in WW2. Which has jack all to do with the female character who isn't even a soldier.
It was just assumed the female character was going to be played less than the male so they half-assed it.
We can do better than JUST generic brown-haired white guys.
https://www.destructoid.com/brown-hair-and-stubble-the-new-face-of-modern-videogames-178442.phtml