Gaming: Pick up and Play or The Epic?

Has anyone noticed a trend lately in game development?

We have near-realism in our graphics (see some screen shots of F.E.A.R or Half-Life - they look incredible), with advanced sound systems that allows us to hear something "behind" us, and artificial intelligence that makes your enemies seem that much more real. Games almost make us feel like we are playing a movie.

Who cares?

Why is it that a simple game, with terrible graphics yet a fun concept, can leave the player entertained for hours?

Yet, after viewing screenshots and attempting to play a game called "Ragdoll Smasher" (see here), I realized that this guy had figured it out. The graphics are simple (at best) and sometimes a bit jerky, and there's no story, but you can sit there for hours throwing bodies around trying to knock over the obstacles.

Another simple yet fun game is "Thermonuclear War" (see here) - basically, you have a bunch of nukes and blackness in which to nuke. Take out all your enemy's cities, you win. It's written using the Windows console, so it's not gorgeous, but interesting nonetheless.

Small and simple games like these can become quite addictive, because you don't need to spend a long time at the computer to be engaged in the gameplay. They're literally pick up and play games. For a casual gamer, such games as Ragdoll Smasher (for the violent types) and Thermonuclear War (for the control freaks) can often be a quick boredom buster.

I don't want to discount the success of Half-Life (or other similarly successful games). They are excellent games and a lot of hard work has been put into them. But if I just want to play for a half an hour, I won't be satisfied with my progress in Half-Life as compared to a win in Thermonuclear War.