Bestsellers in Architecture

Like a gazillion other people, today I got an email with a link to Amazon's Best of 2010. For whatever reason the editors don't have a Top 10 for the architecture subcategory (there is one for the category under which architecture is nested, Art & Photography, but no architecture books are represented), but a glance at the Bestsellers in Architecture reveals the below top 20. What can we learn from this list?

Looks to me like architecture doesn't sell. Interior design comprises most of the list, but only one or two architecture books are found here: Matthew Frederick's hit from MIT Press and a reference book about Revit (I'm inclined to think of #20 more as a baseball book than an architecture book). Most of the books are new, though I'm glad to say Frederick's book came out in 2007, making it something of an anomaly. And what about the first and second spots? Travel/science writer Bill Bryson's "authoritative history of domesticity" ranks 26th in Amazon's Best of 2010.

So, are architecture books too narrow in their audience? Is this architecture category too inclusive of marginally related subjects like interior design and electrical engineering? Are illustrated books that comprise most architecture titles too expensive? Do architects not have enough disposable income these days to buy books? Probably yes on all counts. The sub-subcategories, like criticism and architects a-z, list books more familiarly architectural, but their omission from the parent category's bestsellers are another indication that architecture isn't a bestseller.