The idea that mainstream customers shy away from depth, or only want things that are simplistic, is a fallacy that unfortunately crops up in every medium, not just gaming. But it is contradicted at every turn - by the success of movies like The Dark Knight, a true sensation that is on its way to breaking every record save Titanic's and is wrapped in myriad levels of complexity, or TV shows like Lost, watched religiously across the globe despite its head-twisting, occasionally nonsensical plot.
Products that appeal to as wide an audience as possible are not ones that simple or stupid. Products that are truly mainstream are ones that work on many levels, and can be enjoyed by different people for different reasons. Curiously, this is something that we should really have taken notice of by now, given that it is the core principle behind mega-successes like Super Mario Bros and Tetris, which anyone could understand in two minutes, but which had such layers of depth hidden within them that they are still fun to play today.
One of the real sources of the problem is that modern games are so inaccessible that you require a ten-year gaming education, or the curiosity of an 8-year-old, in order to take it all in. You need to be "core" just to understand what's going on, and the game traditions that are so obvious to us, but baffling to outsiders. Games like Wii Sports or Guitar Hero are popular not because of their perceived lack of depth or simplicity, but because they can instantly be picked up and played by almost anyone, whereas most games utilize every button on a 360 or PS3 controller, often in several different ways.
But almost all we give the less-committed "casual" user are titles that are simple both in interface and in execution - no wonder these games are derided by the "core." It is our inability or unwillingness to sell games to anyone out of the "core" audience that had led to the creation of "casual." But while the division between "core" and "casual" is an inaccurate attempt to break down the massive range of experiences that we know as "video games," an unhelpful "us vs. them" approach, some kind of division beyond our simple genres is becoming necessary. Our poor grasp of what games fundamentally are, with games occupying this strange space between art, toys and sports, is poor, and our genres of FPS, strategy, racer and fighter are really only sub-genres.
We have yet to properly define the true genres of this medium. Lost, the evening news, a documentary on Chinese migrant workers and American Idol have nothing more in common with one another besides being another way to waste an hour in front of the box. In the same way, we do not need to create competition where none exists within games, but accept that there is more than one thing that can be defined as a game. "Core" and "casual" games are clumsy, stuttering attempts to define our growing medium - but they are not the only two potential results in some zero-sum future.
Christian Ward works for a major games publisher, and would be curious to know if anyone has pinpointed exactly when "core" entered the gaming lexicon (and if we can go back in time to stop it from happening).