Why should i geld my stallion?

I have a six year old quarter horse stallion named Kids dark supremo.He is a total gem and is a great show horse. We compete in showmanship, western pleasure and of course halter. Everyone keeps asking me why i never gelded him since i donot breed him. I just dont see the reason why i should have him gelded since he is not aggresive and he is as calm and laid back as most of the geldings i have ever owned. He is kept in a paddock beside my two other horses peanut and mocha chip ( both geldings) and he never gets into fights with them or bullies them around. I take him on trail rides with other horses(mostly mares) and he is the most calmest horse out of the bunch! He is never trying to show off in front of the girls. My niece who is ten years old is even showing him this year and has no problems riding him. Why should i geld my horse when he clearly doesnot need it done?