Since a 357 snub can easily fire any 38 shell you want to feed it, why buy the 38?

I've had this asked of me a few times recently and thought I would post this here to get some opinions. I generally go to "they are lighter" or "they are smaller" but is there something I'm missing?

On a related note, just to make this thread interesting, can we put together some kind of warning label on the ultra light 38's that say "if you are a 120 pound woman this gun will hurt your hand"? Or maybe "if you fire +p loads through this your hand will go numb"?