After narrowly dodging a flock of parakoopas in 3-6, I finally realized why I really love Mario more than any other platformer, especially post-SNES ones. So many other platformers nowadays try to make you think the game is awesome by having you jump through hoops to reach "epic moments," and award your diligence by letting you see a cutscene, or watch as something awesome happens *around* you. The goal in those games is to make you think "that was awesome!"
By contrast Mario never tries to make you think the game is awesome. It creates levels and jumps that you, the player, have to narrowly overcome to advance, and when you finally do you think to yourself "man, I am awesome!" I find that greatly preferable; not only does it create a feeling of empowerment, but it makes it easier for the game to keep topping itself.
Where other platformers have to take the time to manufacture impressive moments (and remember that your sense of what's impressive to watch won't change in three hours), Mario takes advantage of your ever-improving skills to create its great moments. In World 1, your skills are so atrophied that timing your jump to land on that moving koopa so you can reach that high pipe qualifies as an "I'm awesome!" moment; by World 8 you're stringing jumps and timing moves with ease around frentic obstacle courses, which leads to a series of such moments.
Long story short: Mario platformers are like Mushrooms for the mind.
