Why do most parents find it a horrible thing?

to insist their children play outside on a beautiful day? My son's friend had the audacity to chastise me for expecting my children to remain outside and play, soaking up th fresh air and sunshine while it was nice out. She said I was being cruel for not allowing them to come into her house to play video games. What gives? When I was a kid I wasn't allowed in the house on nice days nor did I have the least amount of interest in staying put indoors.