The rise and rise of casual games had been a bit of a mystery to me, especially the myriad similar "match 3" and "hidden object" style of games.  However I'm come to the conclusion that casual games are simply the fast food of the video gaming industry - sure there's no comparison between a hamburger and a T-bone steak, but a hamburger is quicker to make and eat, cheaper to make and eat, and sometimes you're just in the mood for a hamburger.  Ergo, the casual game market appeals to both developers and many game players because development time is shorter, and the game can be played in snack-sized portions - without the controls and strategy learning curve that most complex games have.

In addition, while hidden object games in particular seemed a complete waste of time to me, I've played some now because they've been sent to me for review - and I have to admit, I rather enjoyed them.  This is largely because developers have cleverly integrated simple features of other genres into them, they usually feature attractive visuals and engaging soundtracks, often funny storylines, and are simply fun to play in a very demanding way.

In short, they are not "proper" computer games as such, but they have a place in the market - and they've very much here to stay.