As I work for a Berkshire Hathaway Company, I can tell you that the corporate site is designed as intended. It's not merely frugality. The headquarters staff at Berkshire is small only around a dozen people. That site is easily maintained.
Warren wouldn't see a need to try and promote share value with the corporate web site, and really has very little content to put on it. He's not really interested in casual investors, or frequent traders. So there isn't any flash around the web site. The site really is about the content. When his letter to shareholders goes up, the traffic to it is tremendous. Apart from that not so much.
We used to link to Berkshire's site from ours, and when we had usability tests that involved that part of our content the transition from our site to Berkshire's usually involved jaw dropping expressions.