Believe it or not, but I actually played Mario Bros. the other day. No, not Super Mario Bros. Mario Bros. A really old game that doesn't even have scrolling screens or power ups. In the beginning, I didn't enjoy it very much, after all, all you do is knocking down fleas and turtles in the sewer. Next stage: repeat.
But when the stages got harder, I found Mario Bros. to be increasingly challenging but also satisfying. Even though it's so simple, you need to fully concentrate in order to avoid the fireballs and icicles. You get that "hardcore" feeling that you're really into a game and I kept playing it for a couple of hours! Only reason to keep playing such a simple game for that long was to hunt for a new high score. No achievements. No unlockable weapons or suits. No reward. Not even an ending. Even then, it was a blast to play, and that made me realize something.
When you're really enjoying the gameplay, graphics and story have minimum importance. It could be Mario Bros. HD, which would of course have looked better, but it wouldn't have been more fun to play. Not when you're into it. A good story and great graphics can draw you into a game, but if the gameplay base isn't fun, then it doesn't matter.
What a good story mostly do in games is to provide reasons to keep playing when the gameplay can't keep you interested. Admit it, how many people play Final Fantasy or Mass Effect because of the gameplay? Most people play these kind of games because they are curious about the story. "All right, let's suffer through this sequence too" is not unusual to hear from RPG players when they're advancing through the story.
And when you think about it, some genres haven't changed its gameplay very much the last 15 or so years. Racing games are an exception. But seriously, I don't see much difference in adventure games or action games. The gameplay may be more advanced in certain ways, but today's games don't play drastically different from past games.
My point is, when you're "into" a game, neither graphics or story matter very much. They're only there to draw you in, but many of today's games completely relies on story and visuals to keep the players motivated. A game like Mario Bros. is not very good at drawing you in, which is also why the younger generation can't accept it - it takes way too long time before something "interesting" happens (before the difficulty is increased to make the gameplay interesting).