I was in a similar situation about a year ago, on my way to high school in the morning. I saw a cat die - a set of twitchy furry legs sticking out from underneath the rear bumper of a Mercedes Benz.
Well, I didn't really see it die, the car turned a corner shortly after. But I couldn't eat anything for the rest of the day.
Death under natural circumstances is one of the most beautiful things in the world. I recall watching a documentary on Discovery a few months ago, and there was a clip of a dead fox being overrun with decomposers, fast-forwarded. Watching the fur rot away and the bones reveal themselves gave great catharsis to the moment - a life is taken, and new life is created.
Roadkill, on the other hand, is far from pretty. Not when it lies perfectly still in the middle of a cross-junction with crows picking the entrails out. Not when it is surrounded by little boys poking dried branches at it.
A dried moth or dehydrated frog is one of the prettiest sights anyone is likely to find in the city. In a small city like mine, anyway.