Re:Why do some restaurants...
Hold the pickle, hold the lettuce ...
And while you are at it: hold the mayo, hold the mustard, hold the tomato, hold the barbecue sauce, hold the mushrooms, hold the cheddar. Even then, my family would not be happy with your creation. In fact, you would even have to hold the 6 ounce beef patty to have a burger that everyone in my family would eat.
There is nothing wrong with your perfect burger. However, there is less that 1% of your customers who would agree that your personal preference is their perfect burger.
We live in a BK world, even McDonald's has figured that out.