It IS somehow special now.
While it's true anyone can walk by and see a house, thereby making the outside public, not all houses have the same expected "audience". For example, I live in Chicago. I have zero expectations of privacy on the outside of my unit, because I'm surrounded by 3 million other people.
However, if I move to a tiny town of 20,000 people, I expect the total number of "views" that my house gets will drop substantially. There's an expectation that on a given day, I might not have more than 5 people look at my home. With your home posted online, it becomes trivial for millions of people to see it almost instantly.
I think people concentrate too much on public vs. private, without taking into account the fact that privacy is not binary.
I'm not for censoring data on the web, but it certainly makes sense why some people are, I think justifiably, upset by this. The barrier to to home viewing has dropped from people driving over (for say a fair or special event) to simply clicking (because your house's address got published on Slashdot, Digg, Reddit, etc.).