I would love to have one, if I had the funds and the property to put one on. But I've looked into the pricing of buying and installing one, and they can be quite expensive and labor intensive to install. Just to order the dome and have it shipped to you would cost quite a lot. Plus if you're a homeowner and have one installed on your property, such as in your back yard, I'm not sure if you would get your money back on it if you had to sell your place and move. I don't know if that would have mass appeal to most people, it may sway some people away who perhaps don't like to cook and don't want to be bothered having to demo it and remove it.
Actually, there are quite a few nice alternatives on the market these days that are more convenient. One of them is a table top pizza oven with a built in pizza stone and a dome lid, which gets nearly as hot as an actual pizza oven. Another option is a pizza oven add on for your outdoor grill. It's basically a metal ring that extends the height of your grill and it comes with a pizza stone that rests on it. There is a slot in the side for you to slide the pizza in and out.