> ...spend a whole summer on the PC playing SimCity, Doom (I am old), and later Rainbow Six (I loved that game)...
You're really not THAT old :)
On your main point: I disagree. Even if they don't have "real world results", that doesn't mean that they're not valuable. They have value as cultural products much like books and movies do, but I also think there's an inherent value in "play" itself. It gives us joy, it teaches us how learn new skills, it gives as a practice arena for social interaction, and it exercises the parts our brains dealing complex thinking, spacial reasoning and reaction. It's also just plain fun, and that's not nothing.
You could say playing games "has no value" in the sense that reading a novel "has no value": doing this activity doesn't contribute anything to the world. It's just good for you.
I feel the same way lately. Occasionally I'll fire up a game, play for a while, get bored, and go back to programming. Then I get bored programming because outside of my work, I can't think of what to make... besides games. Or things tangentially related to games, like music synthesizers or things that draw cool effects on the screen.
Oh, and Tetris dreams, I don't miss them one bit. I still get the same effect if I work on a programming problem relentlessly into the night, dreaming in code is torment for me.