"You are not our target demographic!"
In a lot of ways you could look at this as Nintendo was too good in the SNES era of producing games that appealed to a broad spectrum of gamers; developers noticed that Teens continued playing videogames even though (at the time) people considered videogames as a child's toy. Companies like Midway really started targeting the teenage boy demographics with more "Mature" versions of existing games; Mortal Kombat was an inferior version of Street Fighter 2 yet sold amazingly well because teenage boys loved that Sub-Zero could rip off an opponents head and keep the spinal collumn intact. This move into the teen market can be seen as an early version of the blue ocean strategy that Nintendo is focused on.
The success of these pioneers was soon copied by every videogame company except for Nintendo; everyone was focused on the teenage boy market. With Sony entering (and soon dominating) the market the move into teenage boys soon became the 13 to 30 year old male gamer market; soon every game had to push the boundries in order to gain attention to sell better.
In all this time no one noticed how little girls would hit 10 or 11 and stop playing games because there was nothing interesting for them, or that adults who used to play games on occasion left the market, because these companies had found a market which printed money for them.
There is very little alternative content because every successful publisher has focused on the immature male market for so long they have no interest in other markets, and don't have a clue how to make a game which is non-violent.
