Considering who he is and what he is "selling" that's all he needs. Buffet tries to cultivate folksiness and the site goes along with that.

Now take Donald Trump who is of course not as successful as Buffet but his site is much different http://www.trump.com complete with flash or whatever. For what he is trying to sell that's the approach that he needs. He also dresses better than Warren because of what he is objective is.