I've been saying and implementing this for years. Yet certain members of my household have called me lazy for it. I've always felt it was easier to just MOW the leaves rather than waste time raking them. While it's true; I AM lazy, and I hate raking, It's also true that mowing your leaves is actually better for your grass. In fact, Popular Science just backed me up on this and it's about time.
"Popular Science" just did a big write-up on why it's better to hit all those dead leaves with your LAWNMOWER a few times.
The idea is to basically turn them into mulch. Then over the winter, tiny microbes eat the carbon and create nutrients, like nitrogen, phosphorous, and sulfur. Which are all good for your grass. The technical term for it is "mineralization." You might have to mow over them more than once to really chop them up. But if you do, you'll end up with a thicker, healthier lawn in the spring. And it might save time, especially if you have a big yard and a riding mower.
People in areas with a lot of snow just have to make sure they do it before STEADY snow starts to hit. Because when full, un-mulched leaves get covered in snow, it can KILL your grass. Once they're wet, they matte together. Then sunlight can't get in, and it's like a permanent layer of shade. So you just can't wait too long.