I just don't want to open and close it every time I go in and out of the house. If I plan on going inside for more than a couple minutes then I close the garage. I also want it in case it accidentally gets left open. It's rare but will give me peace of mind. Also, in the course of my patrol duties I have discovered that on occasion signals get crossed from other garage door openers and open yours by accident.
For security purposes I also don't have an access code panel on the outside.