People see staying up late as a moral failing and feel that it's their job to guilt trip anyone who sleeps in as lazy and wasting the day away.
People see morning people as industrious and morally superior and don't criticize them for their preferred sleeping habits. At worst they get some ribbing for not being able to stay away for new years, but it's seen as understandable and a more pious lifestyle.
So... Yeah. Morning people wingeing in the comments here can fight me, I'll meet you at 10 o. Clock tonight outside.