Because having to go in for surgery is nothing to be happy about. Expletives are called for upon hearing such news.
Having had about 7 surgeries, a few of them pretty major, I can say it isn't worth the expletives. They don't make the pain go away, nor the scar tissue less. It doesn't even make you feel better about the news, although many trick themselves to think it does. What does help you accept it is realizing that we can't change things and there is Someone who can and who is more concerned with our heart than the words that come out of our mouth - which reflects what is in the heart.