Please understand that at least 70% of console owners at the end of a gen are casual, with casual meaning they play maybe once a week.
Suddenly since the Wii is a big success "casual" seems to have become some kind of magic word, mostly used to describe the Wii in a negative fashion. What is "ignored" is that the PS2 userbase could only become that big because of casuals.
Lots of different types of casuals that is.
Just like in music people buy Britney Spears and people go watch the latest Bruckheimer movie, game-casuals are the regular people.
Some people say that GTA is the epitome of hardcore. Of course this is wrong. It is one of the most casual titles around, together with Madden.
Families with kids, students, young professionals etc all are part of this casual group. Don't be fooled into thinking that the Wii userbase consist mainly of soccer-moms and retired people. Yes Nintendo did an outstanding job to sell their console to them as well, but the majority of owners is male and under 30.