"Why Sony is focusing so much on 'casual' gamers now?" is not the important question ... the real question is "Why did Sony abandon the 'casual' gamer base of the PS2 when they released the PS3?"
Up until this generation, Sony has always catered to the 'casual' gamers more than any other company and (as a result) ended up with the most popular system; Sony's targeting of older teens and young adults (who people didn't consider as gamers at the time) was one of the core reasons why they were successful with the Playstation and PS2. To date the PS3 has been way too expensive, and has had a very weak line-up of games which target 'casual' gamers, so they have been struggling to maintain the userbase they built with previous consoles; I could be wrong, but I suspect the damage has been done and they have no chance of recovering.
