It's actually a difficult thing.
1. The better the site interface, the more work. I just guess Larian puts more work into their games than into their site. <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />
2. The more simple a site interface is, the better it is accessible, especially for handicapped people.
There are devices out there, for blind users, which are *reading* and telling with an artificial voice what's standing on / in a web site. Can you imagine what this device does with a flash-based site ?
It's simple : In HTML pages there is text. In Flash there is no text, which can be used by such a device. So blind people have huge problems using site interfaces which are based on Macromedia Flash, for example.
