It's all part of the image. Buffett gets a lot of miles out of the (authentic or not) aww-shucks folksy homespun image. He can do questionable deals and still not have his integrity questioned, and it's disarming in negotiations, in which, Buffett is as tough as they come.
The image is a funny mix of contrasts. In the 90s, he was living in a $100-200k home that he had lived in for 30 years and drove a pickup truck or crown Vic. But he travelled in a Gulfstream!
A website is a marketing operation. BerkshireHathaway don't really need to do marketing because they're more a legal entity for the purpose of organising things efficiently rather than a business with customers.