Most of what you say here is rather silly. I get the fact that companies are gearing games towards certain generations of social networked teens who have different values over games than us olds do. Mulitplayer trumps single player, because kids play it for longer and there's less design involved.
However, this whole "causal gamers have ruined computers" is where it gets silly. There's a whole range of reasons why game development has gone the way it does. Smaller studios have gone bust, or been bought out by bigger ones. Now, part of this may be the dynamics of the consumer base, but putting it in terms of two distinct groups with their own identities is just not rooted in any kind of reality. It just amounts to you saying "why can't more people be like me?"
The other point is, the beauty of computer games is you don't have to play the most recent now. It's like music. For me, good music largely stopped being made after the early 90's. The handy thing is, I can still listen to that music. JJust like I can still play Sensible World of Soccer, The Nomad Soul, KOTOR and so on, without having to think of it like a crusade against an imagined group of nasty folks called "casuals".