Why isn't usability common sense?

One of the things that has always amazed me is just how many books there are out there about every imaginable web-related topic from programming to strategy to marketing. And of course, there are plenty of books about usability and all its related fields.

Let me emphasize for a moment that I'm talking about BOOKS -- big thick tomes, hundreds (sometimes thousands) of pages long. I can't entirely fathom why they are all necessary. How much can you really say on any of these topics? But, I recognize that there is obviously a market for these books and I'm sure many find them incredibly useful. On that end, I chalk it up to a difference of approach -- most of what I have learned has come from experience and small chunks of learning, but I can certainly appreciate that others learn in a different way.

But the one thing that strikes me is just how much of this knowledge, particularly when it comes to usability, should be common sense but isn't. Certain things require research to determine, and may not be entirely obvious. People scan web pages in an F pattern. The first two words of a list item should carry the informational weight (even if it means poor grammar). Most people find websites via search engines. None of those things are all that surprising, but they're not the kind of things you'd expect the average person to know off-hand.

But what about some of the other, more "obvious" aspects of usability? Tiny fonts are hard to read. Straightforward, descriptive language is easier to understand. Human beings are creatures of habit. All of these things seem like they should be self-evident -- the last of those three is even a common proverb. But take a look online. The web is rampant with sites that use extremely small type, writers bury their content in made-up jargon and unclear, confusing prose, and many designers view it as a personal challenge to always break from traditional designs and interfaces in favor of flashy, unexpected interactions.

If you asked a construction team to build a house, but told them it should have no windows, the door should be a round porthole the size of a hula hoop, and the ceilings should be 4 feet high, you'd be called crazy. But, technically, it would still be a "functional" house, and it would certainly get some attention. A lot of websites seem to fall into this category, often because they are old and poorly made just due to a lack of skill/investment, but some newer websites even fall into this trap, as high-end designers seek to create showy, "interesting" sites that draw in the eye but fail when it comes to actual interaction.

Is it that these common sense ideas aren't common sense after all? Is there an innate drive among designers to always push against commonly-held perceptions? The challenge of anyone with an eye on usability is to recognize that the desire to question the status quo is enormously valuable -- but the ability to look critically at your own "innovative" ideas and recognize when change is a negative is possibly even more beneficial, and is certainly undervalued.

Don't blindly accept "the way things are," but don't abandon common sense in the name of innovative design.