I wouldn't think a company with such a devoted core audience are going to say, "lets get just focus on the casual market and forget about our core fan base" That would be suicide to their business. I think they're just following Nintendo's idea to attract a wider crowd because lets face it the current core audience (For all three companies) aren't going to be gamers forever. A lot of them have lives to focus on (work, kids, family etc)
This is why during the time Nintendo announce the Wii, they said that the gamer audience (in Japan) was shrinking so the best business move was to get more people to play games. They expect that by introducing more people to games through their casual lineup, not all, but a lot of them would start getting into their more mainstream games (Mario, Zelda, etc) and thus become the new "replenished" core audience.
This is when, where, and why the comic book industry had fallen. They pretty much ignored the much younger audience (kids) and started to devote to the older core demographic. They started introducing things like more mature adult like stories, more graphic artwork, darker themes etc. Little kids aren't going to be able to relate to that despite the fact that younger audience often think that everything the older audience likes is "cool." If they didn't ignore the kid demographic earlier, then you would've still seen comics everywhere: New stands, groceries stores, convenience stores, and other non comic bookstore establishments.