Q: I told my wife that it's better to keep the leaves on the lawn as insulation rather than raking them up. She thinks I am just lazy. What do you think?
A: What I think is that I'm going to get into trouble when I answer this question, but NOT with your wife.
Although it's true that the leaves can act as insulation, it's better to rake them off the lawn. If you don't, you can encourage disease problems.
Snow mold - which comes in 2 colors, pink and gray - is likely to develop beneath the matted-down leaves, so you may have the added effort of trying to clear this problem up in the spring. And, you will still have said matted-down leaves to have to clean up, so you might as well get them in fall, when they're easier to deal with.
If you have shrubs, I suggest raking the leaves beneath them. You can also do what I do at home and use the lawn mower to shred the leaves first and then place them under the shrubs, which is much easier to do than bagging the leaves or dragging them out to the curb on a tarp. Besides, shredded leaves are an excellent mulch, so you're doing a good deed for your shrubs in the process.
Sorry, but it's really best that you get the leaves off the lawn. Can I interest you in my old leaf blower?