Why are most architect’s websites rubbish?

I’ve been tempted to start a thread on this for a while. But Lotts raises the same issue in a different thread:
@Lotts wrote:

This raises an interesting point from a web design point of view which applies to a lot of architects websites.
The Gumuchdjian site is not linkable or indexable – as the site is built using Flash. Why on earth would you spend so much money on a web site and have it developed entirely in Flash?
One result is that I can’t link to the image of the boathouse from here – which would be like a free ad for the practice.
But the bigger impact is that searching for the award winning boathouse by name on google will not return the architect’s website in the top 100 results.
Even the very specific search “think tank boathouse gumuchdjian” doesn’t return any link to http://www.gumuchdjian.com
It’s like opting out of all the benefits of the internet. Am I missing something? Why would you do this?

I’ve found such flaws very notable with architects’ websites. I would have fondly imagined that architects, of all people, would generally appreciate the balance between form and function yet nearly all architect’s websites completely sacrifice any sort of usability or respect for the medium for a slick appearance. Computer user interface design has been studied for nearly 30 years and web site usability has been well understood for 10 years yet most architects’ and designers’ websites would score very very poorly if subjected to critical usability analysis. I’m not even going to add to the list of flaws listed above; google “web site usability” if you’re interested in the subject. The mistakes are so fundamental, it is akin to contructing a beautiful building but neglecting to have an entrance or designing a staircase with three foot high steps. It would be like producing printed promotional material but laying out the text with very long lines; it has been well known almost since the invention of typesetting that anything over 100 characters per line is unreadable as most peoples’ eyes cannot scan from the end of one line to the start of the next. It suggests to me an arrogant ignorance of the basic properties of medium and a complete disregard for function.