My impressions about these things are somewhat second hand in that I was never very involved in yard care growing up, but my impression is that even if you like/don't mind the way the leaves look now, they'll be more problematic later. Crisp, fresh leaves are cute; a lawn of mushy, half-decomposed mess will probably be grosser (and will probably make things difficult when you want the grass to grow again the spring, etc.). Also if you care about these things, not raking may annoy your neighbors.

FYI, your town may have some kind moderately helpful leaf collection system (e.g., at one point when I was growing up, we lived somewhere where we gathered our leaves into a giant pile by the side of the road, and the city sent a truck to collect them later. My father was often indignant about them picking times that were inappropriately early or late for the collection).