Peanut is adorable in his picture.
My father has an abdominal hernia that pops in an out, and he has a hiatal hernia, a hole in his diaphragm that allows his stomach to go up into his chest cavity . As Sarah explained, hernias pose a risk of things getting strangulated or pushed around. Benefits and risks are weighed when deciding to do surgery. I believe Peanut's is the type that I would opt to have fixed if our vet recommended it.
Peanut is in my thoughts and prayers.