My take...
Pizza is pizza. It is a distinct set of ingredients put together a certain way to create the item you wish to create. It has a certain look, feel, texture, and flavor. There are extra items you can add, toppings if you will, that compliment it being pizza and tasting like pizza. A pizza's flavor comes from the crust, sauce, and cheese. What compliments that is mushrooms and pepperoni, the long term standard toppings.
Adding something like Buffalo chicken to make Buffalo Chicken Pizza can't be compared to actual pizza. That isn't pizza, it is Buffalo Chicken Pizza, something different. The flavor is the Buffalo chicken rather than the pizza. Same with things like meat lover's pizza. Not pizza, that's just an open face sandwich. This goes with pineapple as well, takes away the flavor of the pizza and makes it something different.
So, if I want pizza, then no, nothing else other than mushrooms or pepperoni. If I wanted Hawaiian pizza or chicken pizza, then I'd get that, but in my eyes it is not pizza. When I want pizza, I want a delicious Italian crust with a good tomato sauce and high quality cheese and perhaps a topping that compliments with the pizza flavor without changing it to something else.