There is something about car racing that makes it the perfect genre for a video game. It's the type of game format that allows for 2-3 minutes of intense concentration (a big race), and you can follow it up with some low-intensity fun (just driving around, exploring the game).
Game makers learned long ago to add a "career" element to most games, so you can feel a sense of progress. Computer-controlled competitors get tougher every race, and you in turn get cash and points to improve the look and performance of your car. You get better as they get better.
I recently read an article that claimed that computer games have gotten a lot easier over time. That is, 99% of gamers that played PacMan could not get past the first few levels, whereas in today's games allow "saves", infinite lives, and are more easily conquered. I don't view this as "the games of today are suckier", but instead as "games have evolved and improved".
For instance, when you play the game Laura Croft Legend, for instance, there are several pre-defined levels. Each level gets tougher. If you had to go back to the beginning each time you died, you would never see the later levels. All of the graphical design and programming work that went in to creating them would be wasted on all but a small number of gamers.
So I don't think it's fair to say that games are easier today than they once were. It's just that the objective of the game has changed. In 1976, a video game was meant to provide 10 minutes or so of entertainment at a time. In fact game designers didn't want you to play for longer than that, since it would cost them money (fewer quarters in the arcade slot per day). Now 30 years later in 2006, games are meant to provide weeks of entertainment. They provide in game prizes for achievement. They provide an incentive for a customer to keep playing them again. The next level is only 1 hour away!
So on my new Xbox 360, I have been finding myself investing dozens of hours in Need for Speed Most Wanted. I am defeating Blacklist guys left, right and center. And I am loving every minute of it.