I consider olive oil, and especially a young, quality olive oil, to be an elegant ingredient. It is more complex and flavorful than other oils and, as a result, is often described and defined by terms and characteristics that are similar to those used to describe and define other complex foods like wine and coffee. For example, you won't see users seeking out specific sources or characteristics of corn oil or canola oil or soybean oil around the world or waxing poetic over these oils. Olive oil also has broad utility. I recall Mario Batali once saying on one of his cable programs that he uses olive oil for just about all recipes calling for oil. I don't believe he pays any attention to smoke points or the like. He just has a love affair with olive oil. No doubt there are many others who are similarly afflicted.
I believe the uniqueness of olive oil has made it an oil of choice for pizza dough, especially where cost is not a consideration. Unless I am following a recipe or reverse engineering a dough calling for a specific type of oil, my first choice for my pizza doughs is olive oil. I generally use the best olive oil I have on hand. Since I don't usually need a lot of olive oil, cost is not a consideration. However, professional pizza operators who would prefer to use olive oil--maybe for the same reasons I do--cannot always ignore its higher cost. As a result, many pizza operators will combine a quality olive oil with another, less expensive oil, like canola oil, or they will use a lower cost pomace grade of olive oil. Some just bite the bullet and use only the best olive oil they can reasonably afford. Usually operators who do this also don't skimp on the other ingredients used to make their pizzas. On the other end of the spectrum are those operators who can only afford to use soybean oil, which is perhaps the cheapest oil, or canola oil, or a combination of those oils. They are usually not trying to make an artisan product.
It's important to keep in mind that not all pizza doughs benefit from using olive oil, especially if too much of it is used. Deep-dish doughs, for example, can use from about 8-25+% oil (by weight of flour). Using all olive oil in such doughs does not necessarily lead to the best eating experience because the olive oil flavor overdominates the crust because of its potent flavor. However, a combination of olive oil and, say, corn oil or canola oil for deep-dish doughs is a big improvement and a common and popular combination. There are also some doughs, especially those with large amounts of yeast that can itself impart a unique flavor to the finished crust, where an oil like olive oil can get lost in the flavor profile. For such doughs, it might be better to use a cheaper oil. There are also doughs that call for no oil whatsoever, such as the classic Neapolitan style dough. However, it is common to drizzle a quality olive oil on the baked Neapolitan pizzas, either before baking or after. One of the benefits of using olive oil this way is that it captures the flavors of the sauces, cheeses and toppings as they bake.
Up to this point I have not mentioned the physical role of oils in pizza doughs. Oil, whether olive oil or some other type of oil, will help coat the gluten structure of the dough and make the dough more plastic and malleable with good rheology characteristics. It will also help produce a greater rise in the dough. When used at high levels and especially if combined with sugar, it will produce a more tender crust and crumb. It will also reduce the likelihood of staling of the crust, although this is usually not an issue with pizza crusts. Oils used in or on doughs can also contribute to crust coloration because of its good heat transfer characteristics.
Different oils are also used to coat pizza pans used to make pan pizzas of various types. Olive oil is often recommended for this purpose, although I am not sure that I would use my very best olive oil for this purpose. I also would not use olive oil to season a pan, mainly because of its low smoke point.